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1.
Finite‐Temperature Properties of Rare‐Earth‐Substituted BiFeO3 Multiferroic Solid Solutions 下载免费PDF全文
Rare‐earth substitution in the multiferroic BiFeO3 (BFO) material holds promise for resolving drawbacks inherent to pure BFO, and for enhancing piezoelectric and magneto‐electric properties via a control of structural and magnetic characteristics. Rare‐earth‐doped BFO solid solutions also exhibit unresolved features, such as the precise nature and atomic characteristics of some intermediate phases. Here, an effective Hamiltonian scheme is developed that allows the investigation of finite‐temperature properties of these systems from an atomistic point of view. In addition to reproducing experimental results of Nd‐doped BFO on structural and magnetic transitions with temperature and composition, this scheme also provides an answer (in form of nanotwins) to these intermediate phases. A striking magneto‐electric effect—namely a paramagnetic–to–antiferromagnetic transition that is induced by an applied electric field—is further predicted near critical compositions, with the resulting structural path being dependent on the orientation of the electric field relative to the antiferroelectric vector. 相似文献
2.
Julius de Rojas Alberto Quintana Aitor Lopeandía Joaquín Salguero Jos L. Costa‐Krmer Llibertat Abad Maciej O. Liedke Maik Butterling Andreas Wagner Lowie Henderick Jolien Dendooven Christophe Detavernier Jordi Sort Enric Menndez 《Advanced functional materials》2020,30(36)
Voltage control of magnetism through electric field‐induced oxygen motion (magneto‐ionics) could represent a significant breakthrough in the pursuit for new strategies to enhance energy efficiency in magnetically actuated devices. Boosting the induced changes in magnetization, magneto‐ionic rates and cyclability continue to be key challenges to turn magneto‐ionics into real applications. Here, it is demonstrated that room‐temperature magneto‐ionic effects in electrolyte‐gated paramagnetic Co3O4 films can be largely increased both in terms of generated magnetization (6 times larger) and speed (35 times faster) if the electric field is applied using an electrochemical capacitor configuration (utilizing an underlying conducting buffer layer) instead of placing the electric contacts at the side of the semiconductor (electric‐double‐layer transistor‐like configuration). This is due to the greater uniformity and strength of the electric field in the capacitor design. These results are appealing to widen the use of ion migration in technological applications such as neuromorphic computing or iontronics in general. 相似文献
3.
In Situ Reversible Ionic Control for Nonvolatile Magnetic Phases in a Donor/Acceptor Metal‐Organic Framework 下载免费PDF全文
Kouji Taniguchi Keisuke Narushima Hajime Sagayama Wataru Kosaka Nanami Shito Hitoshi Miyasaka 《Advanced functional materials》2017,27(5)
Reversible magnetic control by electrical means, which is highly desired from the viewpoint of fundamentals and technological applications such as data storage devices, has been a challenging topic. In this study, the authors demonstrate in situ magnetic phase switching between the ferrimagnetic and paramagnetic states of an electron‐donor/‐acceptor metal‐organic framework (D/A‐MOF) using band‐filling control mediated by the Li+‐ion migration that accompanies redox reactions, i.e., “magneto‐ionic control”. By taking advantage of the rechargeability of lithium‐ion battery systems, in which Li+‐ions and electrons are simultaneously inserted into/extracted from a cathode material, the reversible control of nonvolatile magnetic phases in a D/A‐MOF has been achieved. This result demonstrates that the combination of a redox‐active MOF with porous flexibility and ion‐migration capability enables the creation of new pathways toward magneto‐electric coupling devices in the field of ionics. 相似文献
4.
Long‐Range Nonvolatile Electric Field Effect in Epitaxial Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 Heterostructures 下载免费PDF全文
Cai Zhou Lvkang Shen Ming Liu Cunxu Gao Chenglong Jia Changjun Jiang Desheng Xue 《Advanced functional materials》2018,28(20)
One of the ideal candidates of using electric field to manipulate magnetism is the recently developed multiferroics with emergent coupling of magnetism and electricity, particularly in synthesizing artificial nanoscale ferroelectric and ferromagnetic materials. Here, a long‐range nonvolatile electric field effect is investigated in Fe/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 heterostructure using the dependence of the magnon‐driven magnetoelectric coupling on the epitaxial Fe thin film (4–30 nm) thickness at room temperature using measurements based on the ferromagnetic resonance. The magnon‐driven magnetoelectric coupling tuning of the ferromagnetic resonance field shows a linear response to the electric field, with a resonance field shift that occurs under both positive and negative remanent polarizations, and demonstrates nonvolatile behavior. Moreover, the spin diffusion length of the epitaxial Fe thin film of ≈9 nm is obtained from the results that the change of the cubic magnetocrystalline anisotropy field under different electric fields varies with Fe thickness. These results are promising for the design of future multiferroic devices. 相似文献
5.
Mareike Zink Florian Szillat Uta Allenstein Stefan G. Mayr 《Advanced functional materials》2013,23(11):1383-1391
Due to their magneto‐mechanical coupling and biocompatibility, Fe‐Pd based ferromagnetic shape memory alloys are a highly promising materials class for application as contact‐less magneto‐mechanical transducers in biomedical environments. For use in cell and tissue actuators or strain sensors, sufficient adhesion to mediate strains clearly constitutes a prerequisite. As the RGD sequence is the most important binding motif for mammalian cells, which they express to facilitate adhesion, the potential of RGD coatings to achieve this goal is explored. Employing large‐scale density functional theory calculations the physics of bonding between RGD and Fe‐Pd surfaces, which is characterized by coordinate bonds of O and N atoms to Fe, accompanied by electrostatic contributions, is clarified. Theoretical predictions on adhesion, that are confirmed experimentally, suggest RGD as suitable strain mediator to Fe‐Pd surfaces. On the cell side, favorable adhesion properties of RGD‐coated Fe‐Pd are manifested in cell morphology and spreading behavior. Demonstrating that the adhesion forces between RGD and Fe‐Pd exceed those exerted by cells to the RGD coating, as well as traction forces acting onto integrin bonds, the findings pave the way for novel type of applications as cell and tissue actuator or sensor within the areas of tissue engineering and regenerative medicine. 相似文献
6.
Ke Wang Fang‐Zhou Yao Wook Jo Danka Gobeljic Vladimir V. Shvartsman Doru C. Lupascu Jing‐Feng Li Jürgen Rödel 《Advanced functional materials》2013,23(33):4079-4086
The development of lead‐free piezoceramics has attracted great interest because of growing environmental concerns. A polymorphic phase transition (PPT) has been utilized in the past to tailor piezoelectric properties in lead‐free (K,Na)NbO3 (KNN)‐based materials accepting the drawback of large temperature sensitivity. Here a material concept is reported, which yields an average piezoelectric coefficientd33 of about 300 pC/N and a high level of unipolar strain up to 0.16% at room temperature. Most intriguingly, field‐induced strain varies less than 10% from room temperature to 175 °C. The temperature insensitivity of field‐induced strain is rationalized using an electrostrictive coupling to polarization amplitude while the temperature‐dependent piezoelectric coefficient is discussed using localized piezoresponse probed by piezoforce microscopy. This discovery opens a new development window for temperature‐insensitive piezoelectric actuators despite the presence of a polymorphic phase transition around room temperature. 相似文献
7.
Jerome Vernieres Stephan Steinhauer Junlei Zhao Audrey Chapelle Philippe Menini Nicolas Dufour Rosa E. Diaz Kai Nordlund Flyura Djurabekova Panagiotis Grammatikopoulos Mukhles Sowwan 《Advanced functional materials》2017,27(11)
Magnetron‐sputtering inert‐gas condensation is an emerging technique offering single‐step, chemical‐free synthesis of nanoparticles with well‐defined morphologies optimized for specific applications. In this study, the authors report a flexible approach to produce Fe nanocubes as building blocks for high‐performance NO2 gas sensor devices, and hybrid FeAu nanocubes with magneto‐plasmonic properties. Considering that nucleation happens within a short distance from the sputtering target, the authors utilize the high‐permeability and resultant screening effect induced by magnetic Fe targets of various thicknesses to manipulate the magnetic field configuration and plasma confinement. The authors thus readily switch from bimodal to single‐Gaussian size distributions of Fe nanocubes by modifying their primordial thermal environments, as explained by a combination of modeling methods. Simultaneously, the authors obtain a material yield increase of more than one order of magnitude compared to experiments using postgrowth mass filtration. The effectiveness of the method is demonstrated by the deposition of Fe nanocubes on microhotplate devices, leading to unprecedented NO2 detection performance for Fe‐based chemoresistive gas sensors. The exceedingly low detection limit down to 3 ppb is attributed to a morphological change in operando from Fe/Fe‐oxide core/shell to specific hollow‐nanocube structures, as revealed by in situ environmental transmission electron microscopy. 相似文献
8.
Multiferroic Polymer Laminate Composites Exhibiting High Magnetoelectric Response Induced by Hydrogen‐Bonding Interactions 下载免费PDF全文
Jiezhu Jin Fang Zhao Kuo Han M. A. Haque Lijie Dong Qing Wang 《Advanced functional materials》2014,24(8):1067-1073
The coupling of the magnetic, electric, and elastic properties in multiferroics creates new collective phenomena and enables next‐generation device paradigms. In this work, the hydrogen bonding interaction between hydrate salts and ferroelectric polymers is exploited in the development of high‐performance magnetoelectric (ME) polymer laminate composites. The microstructures and crystallite structures of the Al(NO3)3·9H2O doped poly(vinylidene fluoride‐co‐hexafluoropropylene), P(VDF‐HFP), are carefully studied. The effect of hydrogen bonding interaction on the polarization ordering of the ferroelectric polymers is investigated by 2D wide‐angle X‐ray diffraction, polarized Fourier transform infrared spectra, and dielectric spectra at varied frequencies and temperatures. It is found that hydrogen bond not only promotes the formation of the polar crystallite phase but also improves the polarization ordering in the ferroelectric polymer, which subsequently increases the remnant polarization of the polymers as verified in the polarization‐electric field loop measurements. These entail marked improvement in the ME voltage coefficients (αME) of the resulting polymer laminate composites based on ferromagnetic Metglas relative to analogous composites. The composite exhibits a state‐of‐the‐art αME value of 20 V cm‐1 Oe under a dc magnetic field of ≈4 Oe and a colossal αME of 320 V cm‐1 Oe at a frequency of 68 kHz. 相似文献
9.
Yuta Kashiwabara Masaki Nakano Yuji Nakagawa Yue Wang Hideki Matsuoka Yoshihiro Iwasa 《Advanced functional materials》2019,29(17)
Emergent properties of 2D materials attract considerable interest in condensed matter physics and materials science due to their distinguished features that are missing in their bulk counterparts. A mainstream in this research field is to broaden the scope of material to expand the horizons of the research area, while developing functional interfaces between different 2D materials is another indispensable research direction. Here, the emergence of electrical conduction at the interface between insulating 2D materials is demonstrated. A new class of van der Waals heterostructures consisting of two sets of insulating transition‐metal dichalcogenides, group‐VI WSe2 and group‐IV TMSe2 (TM = Zr, Hf), is developed via molecular‐beam epitaxy, and it is found that those heterostructures are highly conducting although all the constituent materials are highly insulating. The WSe2/ZrSe2 interface exhibits more conducting behavior than the WSe2/HfSe2 interface, which can be understood by considering the band alignments between constituent materials. Moreover, by increasing Se flux during heterostructure fabrication, the WSe2/ZrSe2 interface becomes more conducting, reaching nearly metallic behavior. Further improvement of the crystalline quality as well as exploring different material combinations are expected to lead to metallic conduction, providing a novel functionality emerging at van der Waals heterostructures. 相似文献
10.
Natascha Kuhl Stefan Bode Ranjita K. Bose Jürgen Vitz Andreas Seifert Stephanie Hoeppener Santiago J. Garcia Stefan Spange Sybrand van der Zwaag Martin D. Hager Ulrich S. Schubert 《Advanced functional materials》2015,25(22):3295-3301
The utilization of dynamic covalent and noncovalent bonds in polymeric materials offers the possibility to regenerate mechanical damage, inflicted on the material, and is therefore of great interest in the field of self‐healing materials. For the design of a new class of self‐healing materials, methacrylate containing copolymers with acylhydrazones as reversible covalent crosslinkers are utilized. The self‐healing polymer networks are obtained by a bulk polymerization of an acylhydrazone crosslinker and commercially available methacrylates as comonomers to fine‐tune the Tg of the systems. The influence of the amount of acylhydrazone crosslinker and the self‐healing behavior of the polymers is studied in detail. Furthermore, the basic healing mechanism and the corresponding mechanical properties are analyzed. 相似文献
11.
Hybrid Improper Ferroelectricity in Multiferroic Superlattices: Finite‐Temperature Properties and Electric‐Field‐Driven Switching of Polarization and Magnetization 下载免费PDF全文
Bin Xu Dawei Wang Hong Jian Zhao Jorge Íñiguez Xiang Ming Chen Laurent Bellaiche 《Advanced functional materials》2015,25(24):3626-3633
The so‐called hybrid improper ferroelectricity (HIF) mechanism allows to create an electrical polarization by assembling two nonpolar materials within a superlattice. It may also lead to the control of the magnetization by an electric field when these two nonpolar materials are magnetic in nature, which is promising for the design of novel magneto‐electric devices. However, several issues of fundamental and technological importance are presently unknown in these hybrid improper ferroelectrics. Examples include the behaviors of its polarization and dielectric response with temperature, and the paths to switch both the polarization and magnetization under electric fields. Here, an effective Hamiltonian scheme is used to study the multiferroic properties of the model superlattice (BiFeO3)1/(NdFeO3)1. Along with the development of a novel Landau‐type potential, this approach allows to answer and understand all the aforementioned issues at both microscopic and macroscopic levels. In particular, the polarization and dielectric response are both found to adopt temperature dependences, close to the phase transition, that agree with the behavior expected for first‐order improper ferroelectrics. And most importantly, a five‐state path resulting in the switching of polarization and magnetization under an electric field, via the reversal of antiphase octahedral tiltings, is also identified. 相似文献
12.
Composite materials containing both ferroelectric and ferromagnetic phases have been synthesized from nanometer‐sized powders of BaTiO3 (ferroelectric phase) and NiCuZn ferrite (ferromagnetic phase) by a standard ceramic method. The coexistence of magnetic and electric hysteresis in the composite material has been observed at room temperature. Upon the application of magnetic and electric fields, the magnetization and electric polarization of the composite material can easily be tuned based on the changing BaTiO3 content of the materials studied. These composite materials exhibit both excellent dielectric and soft‐magnetic properties with a variation of the frequency. Our results strongly suggest that this composite material may be the best candidate for the development of truly integrated passive filters. Due to the combination of both inductance and capacitance in one material, the adoption of an integrated passive filter could greatly reduce the size of printed circuit boards and could efficiently suppress electromagnetic interference, thereby enabling significant miniaturization of electronic elements and devices. 相似文献
13.
S. H. Lim M. Murakami W. L. Sarney S. Q. Ren A. Varatharajan V. Nagarajan S. Fujino M. Wuttig I. Takeuchi L. G. Salamanca‐Riba 《Advanced functional materials》2007,17(14):2594-2599
Multiferroic epitaxial Bi‐Fe‐O thin films of different thicknesses (15–500 nm) were grown on SrTiO3 (001) substrates by pulsed laser deposition under various oxygen partial pressures to investigate the microstructural evolution in the Bi‐Fe‐O system and its effect on misfit strain relaxation and on the magnetic properties of the films. Films grown at low oxygen partial pressure show the canted antiferromagnetic phase α‐Fe2O3 embedded in a matrix of BiFeO3. The ferromagnetic phase, γ‐Fe2O3 is found to precipitate inside the α‐Fe2O3 grains. The formation of these phases changes the magnetic properties of the films and the misfit strain relaxation mechanism. The multiphase films exhibit both highly strained and fully relaxed BiFeO3 regions in the same film. The magnetization in the multiphase Bi‐Fe‐O films is controlled by the presence of the γ‐Fe2O3 phase rather than heteroepitaxial strain as it is the case in pure single phase BiFeO3. Also, our results show that this unique accommodation of misfit strain by the formation of α‐Fe2O3 gives rise to significant enhancement of the piezo electric properties of BiFeO3. 相似文献
14.
Z. Shi S. Hau J. Luo T.‐D. Kim N. M. Tucker J.‐W. Ka H. Sun A. Pyajt L. Dalton A. Chen A. K.‐Y. Jen 《Advanced functional materials》2007,17(14):2557-2563
One of the most challenging tasks encountered in developing highly efficient electro‐optic (EO) devices is to find a material system that possesses all desirable properties such as large EO coefficients, good thermal and mechanical stability, and low optical loss. In order to meet this stringent requirement, we have developed a series of crosslinkable EO dendrimers using the standardized AJL8 ‐type chromophore as the center core and the furyl‐ and anthryl‐containing dendrons as the periphery. Upon adding a trismaleimide ( TMI ) dienophile, these dendrimers could be in‐situ crosslinked via the Diels–Alder cycloaddition and efficiently poled under a high electric field. Through this dynamic process, the spatially voided and π‐electron‐rich surrounding of the chromophore core changes into a dense and more aliphatic network, with the dipolar chromophore embedded and aligned inside. The resultant materials exhibit large EO coefficients (63–99 pm V–1 at 1.31 μm), excellent temporal stability (the original r33 values remain unchanged at 100 °C for more than 500 h), and blue‐shifted near‐IR absorption. With these combined desirable properties, a poled EOD2/TMI film could be processed through multiple lithographic and etching steps to fabricate a racetrack‐shaped micro‐ring resonator. By coupling this ring resonator with a side‐polished optical fiber, a novel broadband electric‐field sensor with high sensitivity of 100 mV m–1 at 550 MHz was successfully demonstrated. 相似文献
15.
Atomic‐Scale Visualization of Polarization Pinning and Relaxation at Coherent BiFeO3/LaAlO3 Interfaces 下载免费PDF全文
Rong Huang Hang‐Chen Ding Wen‐I Liang Yong‐Chao Gao Xiao‐Dong Tang Qing He Chun‐Gang Duan Ziqiang Zhu Junhao Chu Craig A. J. Fisher Tsukasa Hirayama Yuichi Ikuhara Ying‐Hao Chu 《Advanced functional materials》2014,24(6):793-799
Complex oxide heterointerfaces, which play host to an incredible variety of interface physical phenomena, are of great current interest in introducing new functionalities to systems. Here, coherent super‐tetragonal BiFeO3/LaAlO3 and rhombohedral BiFeO3/LaAlO3 heterointerfaces are investigated by using a combination of high‐angle annular dark‐field (HAADF) imaging and annular bright‐field (ABF) imaging in a spherical aberration (Cs) corrected scanning transmission electron microscope (STEM), and first‐principles calculations. The complicated ferroelectric polarization pinning and relaxation that occurs at both interfaces is revealed with atomic resolution, with a dramatic change in structure of BiFeO3, from cubic to super‐tetragonal‐like. The results enable a detailed explanation to be given of how non‐bulk phase structures are stabilized in thin films of this material. 相似文献
16.
Jongwook Kim Alexis de la Cotte Rodolphe Deloncle Samuel Archambeau Claudine Biver Jean‐Paul Cano Khalid Lahlil Jean‐Pierre Boilot Eric Grelet Thierry Gacoin 《Advanced functional materials》2012,22(23):4949-4956
Mineral liquid crystals are materials in which mineral's intrinsic properties are combined with the self‐organization behavior of colloids. However, the use of such a system for practical application, such as optical switching, has rarely been demonstrated due to the fundamental drawbacks of colloidal systems such as limited dispersion stability. Studying colloidal suspensions of LaPO4 nanorods, it is found that drastic improvement of colloidal stability can be obtained through a transfer of particles from water towards ethylene glycol, thus enabling the investigation of liquid crystalline properties of these concentrated suspensions. Using polarization microscopy and small‐angle x‐ray scattering (SAXS), self‐organization into nematic and columnar mesophases is observed enabling the determination of the whole phase diagram as a function of ionic strength and rod volume fraction. When an external alternative electric field is applied, a very efficient orientation of the nanorods in the liquid‐crystalline suspension is obtained, which is associated with a significant optical birefringence. These properties, combined with the high colloidal stability, are promising for the use of such high transparent and athermal material in electro‐optical devices. 相似文献
17.
After decades of study, BiFeO3 is still the most promising single‐phase multiferroic material due to its large polarization and high operating temperature, drawing much attention. As a typical type‐I multiferroic material, the magnetoelectric coupling in BiFeO3 is deemed to be weak due to the different origins of its ferroelectricity and magnetism. Here, the magnetoelectric effect in bulk BiFeO3 is readdressed both theoretically and experimentally. Based on the Dzyaloshinsky–Moriya interaction scenario, the magnetoelectric effect in BiFeO3 is actually strong, with a coupling energy of about 1.25 meV and a magnetism‐coupled parasitic polarization comparable to that of the type‐II multiferroics. However, such strong magnetoelectric coupling also causes the cycloidal spin structure, which inhibits the observation of linear magnetoelectric coupling in bulk BiFeO3. To resolve this contradiction, Sm‐substitution is utilized to suppress the magnetoelectric effect and unlocks the weak ferromagnetism. At an optimized composition, such a weak ferromagnetic state can be switched back to the cycloidal state by an electric field, thus realizing electrical control of the magnetism. It has been argued that field‐controlled phase transition is a promising path to colossal magnetoelectric effect. It is of pioneering significance for further investigations down this road. 相似文献
18.
A novel concept is proposed to synthesize a new class of composites featuring magnetic, molecular sieve and metallic nanoparticle properties. These multi‐functional materials have potential applications as recyclable catalysts, disinfectants and sorbents. The magnetic property enables effective separation of the spent composites from complex multiphase systems for regeneration and recycle, safe disposal of the waste and/or recovery of loaded valuable species. The zeolite molecular sieve provides a matrix which supports a remarkably new, simple, efficient and economical method to make stable, supported silver nanoparticles by silver ion exchange and controlled thermal reduction. The silver nanoparticles generated in this way have excellent properties such as high reactivity and good thermal stability without aggregation, which act as nano reactors for desired functionality in a wide range of applications. Magnetic component (Fe3O4), molecular sieve matrix (zeolite) and silver nanoparticles generated by ion exchange followed by controlled reduction, together form this unique novel composite with designed functions. It represents a practically operational, economical, sustainable and environmentally friendly new advanced functional material. This paper focuses on the novel synthesis and characterization of the composite, with an example of applications as sorbents for the removal of vapor‐phase mercury from the flue gas of coal‐fired power plants. 相似文献
19.
Shiru Wang Mingke Yao Zirun Li Chun Feng Lei Wang Xiaolei Tang Peng Kang Bin Zhang Wenbo Mi Guanghua Yu 《Advanced functional materials》2019,29(4)
Modulating the orbital configuration of ferromagnetic metal (FM)/metal‐oxide (MO) interfaces is crucial for obtaining a controllable interfacial magnetism for constructing energy‐efficient magnetic memory and logic devices. The traditional works of orbital regulation depend on external fields, such as electric field, temperature field, and stress field. This work proposes a novel orbital modulation strategy by modifying the coordination environment of FM/MO interface with nitrogen (N) incorporation. By preparing a Fe/MgO bilayer at a N2 atmosphere, N atoms occupy the interstitial sites of the Fe lattice, which induces a charge redistribution at the Fe/MgO interface and toggles a prominent orbital reconstruction of Fe with an increment of out‐of‐plane orbital occupancy. Therefore, the orbital magnetism is tuned effectively, which remarkably strengthens the interfacial magnetic anisotropy energy by 0.6 erg cm?2 and enables a broad magnetic anisotropy tunability from in‐plane to perpendicular direction. Besides, the Fe thickness for maintaining perpendicular magnetic anisotropy extends from less than 1 to 3 nm, which is favorable for improving the signal‐to‐noise ratio and stability of devices in nanoscale. These findings provide an external‐field‐independent strategy of orbital engineering for tailoring obit‐controlled performance at FM/MO heterointerfaces, which practically advances the magnetic storage and logic devices. 相似文献
20.
We study the photorefractive (PR) properties of a new kind of low glass‐transition temperature (Tg) polymer composite based on layered photoconductive polymers, poly(p‐phenylene terephthalate) carbazoles (PPT‐CZs). These photoconductors consist of the rigid backbone of PPT with pendant oxyalkyl CZ groups. The compounds are doped with the photosensitizer C60 and nonlinear optical chromophores diethylaminodicyanostyrene (DDCST), and no plasticizers are added. When the host polymers are mixed with various PR ingredients, the layers are preserved and their layer distance increases, indicating that all the guest molecules are confined to the nanoscale interlayer space. These composites showed very low Tg values (< ? °C). Despite the absence of a plasticizer and the lower concentration of the carbazole photoconductive moieties as compared to poly(N‐vinylcarbazole) systems, these materials show excellent PR properties, i.e., a PR gain of Γ = 250 cm–1 under an external electric field of 60 V μm–1, and diffraction efficiency and PR sensitivity of 93 % and 24 ± 7 cm2 kJ–1 at E = 100 V μm–1, respectively. 相似文献