金红石型纳米TiO2的液相激光烧蚀合成

利用浸入聚乙烯基吡咯烷酮(PVP)水溶液中的金属钛片为靶材,采用1064nm红外脉冲激光进行液相激光烧蚀制备了金红石型纳米TiO2。应用XRD、TEM、HRTEM和Raman对产物进行表征,并对其形成机理进行了探讨。结果表明:金红石型纳米TiO2可通过液相激光烧蚀法在室温下一步合成,颗粒平均粒径约50nm,尺寸分布比较窄,分散性较好。脉冲激光诱导的瞬间等离子体可能是金红石型纳米TiO2形成的主要原因。     

Interfacial Connections between Organic Perovskite/n+ Silicon/Catalyst that Allow Integration of Solar Cell and Catalyst for Hydrogen Evolution from Water

The rapidly increasing solar conversion efficiency (PCE) of hybrid organic–inorganic perovskite (HOIP) thin-film semiconductors has triggered interest in their use for direct solar-driven water splitting to produce hydrogen. However, application of these low-cost, electronic-structure-tunable HOIP tandem photoabsorbers has been hindered by the instability of the photovoltaic-catalyst-electrolyte (PV+E) interfaces. Here, photolytic water splitting is demonstrated using an integrated configuration consisting of an HOIP/n⁺silicon single junction photoabsorber and a platinum (Pt) thin film catalyst. An extended electrochemical (EC) lifetime in alkaline media is achieved using titanium nitride on both sides of the Si support to eliminate formation of insulating silicon oxide, and as an effective diffusion barrier to allow high-temperature annealing of the catalyst/TiO₂-protected-n⁺silicon interface necessary to retard electrolytic corrosion. Halide composition is examined in the (FA_1-xCs_x)PbI₃ system with a bandgap suitable for tandem operation. A fill factor of 72.5% is achieved using a Spiro-OMeTAD-hole-transport-layer (HTL)-based HOIP/n⁺Si solar cell, and a high photocurrent density of −15.9 mA cm⁻² (at 0 V vs reversible hydrogen electrode) is attained for the HOIP/n⁺Si/Pt photocathode in 1 m NaOH under simulated 1-sun illumination. While this thin-film design creates stable interfaces, the intrinsic photo- and electro-degradation of the HOIP photoabsorber remains the main obstacle for future HOIP/Si tandem PEC devices.     

TiO2纳米粉体的烧结行为及其性能的研究

分别采用Ti(SO4)2、TiOCl2沸腾回流直接水解制得了纯锐钛矿型和混晶的纳米TiO2。用XRD、SEM对不同煅烧温度下的纳米TiO2粉末结构、粒径大小进行了表征。结果表明:混晶中的锐钛矿相转变温度(500℃)明显低于纯锐钛矿相的(600℃以上)。纳米TiO2粉末的光催化活性与煅烧温度密切相关,500℃煅烧的混晶结构的纳米TiO2粉体表现出较高的光催化活性,20 min催化氧化降解率达到92.3%。     

CNT对BST陶瓷微波介电性能的影响

采用XRD及SEM研究(Ca0.61Nd0.26)TiO3对微波介质陶瓷Ba4Sm9.33Ti18O54的结构和微波介电性能的影响。获得了一些性能较好的微波介质陶瓷(1–x)Ba4Sm9.33Ti18O54-x(Ca0.61Nd0.26)TiO3,其微波介电性能如下:εr=75,Q·f为8985GHz,τf为–8.2×10–6℃–1(x?=0);εr为75,Q·f为9552GHz,τf为–14.4×10–6℃–1(x?=0.2)。     

B2O3掺杂对Ba0.6Sr0.4TiO3/MgO陶瓷介电性能的影响

采用XRD和SEM对B2O3掺杂Ba0.6Sr0.4TiO3/MgO(简称为BSTM)陶瓷致密化行为和介电性能进行了研究。结果表明:掺杂适量B2O3可明显降低BSTM陶瓷的烧结温度,在1480℃时即可烧结致密化,比未掺杂的BSTM陶瓷烧结温度降低70℃;掺杂量不同,则B2O3在陶瓷体中的存在形式不同,引起其介电性能相应变化;1480℃下烧结,B2O3掺杂量为0.8%(质量分数)时,10kHz下测得试样的εr为138,tanδ为0.0034,εr可调率达12.6%(3MV/m),性能有所提高。     

低团聚掺锑氧化锡纳米微粉的制备

以SnCl4?5H2O和SbCl3乙醇溶液为原料,用阴离子树脂交换除氯水解法制得无Cl–的掺锑氢氧化锡胶体沉淀。并用乙酸异戊酯作脱水剂。结果表明,用乙酸异戊酯共沸蒸馏干燥法能有效防止粉体的硬团聚,得到了比表面积为284.43m2/g掺锑氢氧化锡微粉。热处理后得到了低硬团聚、电阻率为0.405?·cm的掺锑氧化锡纳米晶体。     

聚合物前驱体法制备CTNA陶瓷及其性能

采用DSC-TGA、XRD和SEM对聚合物前驱体法制备的0.7CaTiO_3-0.3NdAlO_3(CTNA)陶瓷粉末进行了分析。结果表明:经550℃预烧后的粉末为无定形态;但是当预烧温度提高到600℃时,形成了钙钛矿结构的CTNA单相。这表明CTNA晶相是未经中间相而直接从无定形态的前驱体中结晶形成。与传统固相反应法相比,合成温度从1300℃大幅下降到600℃。经900℃预烧,1375℃烧结的样品,其εr为43.3,Q·f为34862GHz,τf为1.4×10–6℃~(–1)。     

高频电介质新材料Ba2Ti3Nb4O18陶瓷

采用氧化物固相反应法制备了理论密度达96.8%以上的Ba2Ti3Nb4O18高频电介质陶瓷。XRD和SEM分析表明:该陶瓷为两相混合结构,主晶相为单斜Ba2Ti3Nb4O18相,次晶相为六方Ba3Ti4Nb4O21相。1250℃/2h烧结瓷体Ba3Ti4Nb4O21相的体积分数为5%~8%,1MHz下的介电性能为:εr约为38,tanδ约为1.6×10–4,αC约为–8.51×10–6/℃。     

SnO2对锂铌钛系微波介电陶瓷性能的影响

用SnO2作为掺杂剂对LiNb0.6Ti0.5–xSnxO3陶瓷进行改性,研究了SnO2添加量对LiNb0.6Ti0.5O3锂铌钛体系陶瓷的烧结性能,显微结构和微波介电性能的影响。结果表明:随着SnO2添加量的增加,陶瓷体密度和介电常数基本保持不变;而Q·f值随SnO2的加入有所提高,而后随SnO2含量继续增加而快速下降;在1100℃的烧结温度下,当x为0.01时,获得微波介电性能优良的微波陶瓷,其εr为67.8,τf为+4×10–6/℃,Q·f为6780GHz。