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Solid solutions (1-x)PbMg1/3Nb2/3O3 + xPbCd1/3Nb2/3O3 with x = 0-0.30 are investigated with purpose to work out a capacitor ceramics with good dielectric properties and low sintering temperature. It is found that the perovskite phase forms at sintering near to 980°C and begins to decompose at higher temperatures. When x grows from 0 to 0.30, the Curie temperature linearly grows from -10°C to +25°C, the dielectric permittivity εm in the Curie point TC decreases from 18000 to 6800 and the phase transition becomes more diffused. The dielectric permittivity at room temperature is rather high and the temperature stability is improved. The system is of interest, because it can serve as a base for working out some ceramic materials for capacitors with low sintering temperature, which needs of no special atmosphere at burning.  相似文献   

3.
以2,2-二溴甲基丙醇(BBMP)为初始原料,通过与碱发生关环反应生成3-溴甲基-3-甲基氧杂环丁烷(BrMMO)。讨论了碱的种类和用量对BBMP关环产率的影响以及反应体系中碱的浓度、反应温度和反应时间对合成BrMMO产率的影响。通过实验确定的最佳工艺条件为:BBMP与NaOH摩尔比为1.0∶1.1,NaOH醇溶液的质量分数为12%,反应温度为78℃,反应时间为4h时,BrMMO产率为65%。最终产品经元素分析、IR和1HNMR检测确定为BrMMO。该试验工艺简单,原料易得,且溶剂便于回收、污染小。  相似文献   

4.
3-叠氮甲基-3-甲基氧丁环的合成   总被引:10,自引:6,他引:4  
以三羟甲基乙烷与碳酸二乙酯为原料,经环化反应合成了3-羟甲基-3-甲基氧丁环(HMM O)。在低温下,HMM O与对甲苯磺酰氯反应生成3-磺酸酯甲基-3-甲基氧丁环(M TM O)。M TM O和叠氮化钠发生叠氮化反应形成叠氮单体3-叠氮甲基-3-甲基氧丁环(AMM O)。三步反应收率分别为76%,96%,85%。用核磁、红外、元素分析和DSC表征了化合物的结构与性能。结构鉴定表明为目标化合物AMM O。  相似文献   

5.
以2,2-二溴甲基丙醇(BBMP)为初始原料,通过与碱发生关环反应生成3-溴甲基-3-甲基氧杂环丁烷(BrMMO).讨论了碱的种类和用量对BBMP关环产率的影响以及反应体系中碱的浓度、反应温度和反应时间对合成BrMMO产率的影响.通过实验确定的最佳工艺条件为:BBMP与NaOH摩尔比为1.0∶1.1,NaOH醇溶液的质量分数为12%,反应温度为78℃,反应时间为4 h时,BrMMO产率为65%.最终产品经元素分析、IR和1HNMR检测确定为BrMMO.该试验工艺简单,原料易得,且溶剂便于回收、污染小.  相似文献   

6.
The compounds TlMnCl3, TlFeCl3, TlCoCl3 and TlNiCl3 were prepared by heating T1C1 with the corresponding transition metal dichloride in an evacuated ampoule. Atomic positions were determined from powder photographs. All four compounds were found to be related to the perovskite type structure. TlMnCl3 has a cubic structure, space group Pm3m, with ao = 5.025 Å. The other three compounds are hexagonal, probable space group P63mc, with cell dimensions (in Å) a0 = 6.976 and c0 = 6.008 for the Fe compound, a0 = 6.907 and c0 = 5.981 for the Co compound and a0 = 6.863 and c0 = 5.881 for the Ni compound. The three hexagonal compounds are isomorphous. A measureable concentration of basal plane stacking faults was found to occur in TlFeCl3 and also, to a lesser degree, in TlCoCl3.  相似文献   

7.
LaScO3:xBi3+,yTb3+,zEu3+ (x = 0 − 0.04, y = 0 − 0.05, z = 0 − 0.05) phosphors were prepared via high-temperature solid-state reaction. Phase identification and crystal structures of the LaScO3:xBi3+,yTb3+,zEu3+ phosphors were investigated by X-ray diffraction (XRD). Crystal structure of phosphors was analyzed by Rietveld refinement and transmission electron microscopy (TEM). The luminescent performance of these trichromatic phosphors is investigated by diffuse reflection spectra and photoluminescence. The phenomenon of energy transfer from Bi3+ and Tb3+ to Eu3+ in LaScO3:xBi3+,yTb3+,zEu3+ phosphors was investigated. By changing the ratio of x, y, and z, trichromatic can be obtained in the LaScO3 host, including red, green, and blue emission with peak centered at 613, 544, and 428 nm, respectively. Therefore, two kinds of white light-emitting phosphors were obtained, LaScO3:0.02Bi3+,0.05Tb3+,zEu3+ and LaScO3:0.02Bi3+,0.03Eu3+,yTb3+. The energy transfer was characterized by decay times of the LaScO3:xBi3+, yTb3+, zEu3+ phosphors. Moreover absolute internal QY and CIE chromatic coordinates are shown. The potential optical thermometry application of LaScO3:Bi3+,Eu3+ was based on the temperature sensitivity of the fluorescence intensity ratio (FIR). The maximum Sa and Sr are 0.118 K−1 (at 473.15 K) and 0.795% K−1 (at 448.15 K), respectively. Hence, the LaScO3:Bi3+,Eu3+ phosphor is a good material for optical temperature sensing.  相似文献   

8.
赵宙兴  叶大钧 《化学试剂》2012,34(8):756-758
以苯甲酰氯、四氯化碳、间甲基苯甲酰氰为原料,合成了标题化合物。重点考察了氰化过程中不同原料配比、反应温度、时间、溶剂和催化剂用量对收率的影响。实验结果表明,其最佳反应条件为:n(1,1,2-三氯-2-苯基乙烯)∶n(3-甲基苯甲酰氰)=1∶1.2,二氯甲烷为反应溶剂,3 mmol催化剂三乙胺,室温反应5 h,总收率达80.6%。  相似文献   

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10.
Thermal analyses of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB–HV)], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB–HHx)] were made with thermogravimetry and differential scanning calorimetry (DSC). In the thermal degradation of PHB, the onset of weight loss occurred at the temperature (°C) given by To = 0.75B + 311, where B represents the heating rate (°C/min). The temperature at which the weight-loss rate was at a maximum was Tp = 0.91B + 320, and the temperature at which degradation was completed was Tf = 1.00B + 325. In the thermal degradation of P(HB–HV) (70:30), To = 0.96B + 308, Tp = 0.99B + 320, and Tf = 1.09B + 325. In the thermal degradation of P(HB–HHx) (85:15), To = 1.11B + 305, Tp = 1.10B + 319, and Tf = 1.16B + 325. The derivative thermogravimetry curves of PHB, P(HB–HV), and P(HB–HHx) confirmed only one weight-loss step change. The incorporation of 30 mol % 3-hydroxyvalerate (HV) and 15 mol % 3-hydroxyhexanoate (HHx) components into the polyester increased the various thermal temperatures To, Tp, and Tf relative to those of PHB by 3–12°C (measured at B = 40°C/min). DSC measurements showed that the incorporation of HV and HHx decreased the melting temperature relative to that of PHB by 70°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 90–98, 2001  相似文献   

11.
This paper reports the photoluminescence spectral properties of Eu3+, Tb3+, Dy3+ and Ho3+ doped LaOX, YOX, (La, Gd)OX, and (La, Y)OX (X=F, Cl) powder phosphors. Under the UV-light these phosphors have exhibited bright reddish-orange, green, yellowish-blue and bluish-green colours. This papers also describes the effects of the halides change in the host material chosen specifically.  相似文献   

12.
Ba3Tb(BO3)3:Eu3+的制备与发光性质   总被引:2,自引:1,他引:1  
采用高温固相法合成了Ba3Tb(BO3)3:Eu3+红色荧光粉,并研究了Ba3Tb(BO3)3:Eu3+的发光特性。Ba3Tb(BO3)3:Eu3+的激发光谱包含250nm~330nm和350nm~400nm的2个宽带,最大峰值位于383nm,可以被紫外-近紫外发光二极管(light-emitting diodes,LED)有效激发。Ba3Tb(BO3)3:Eu3+的发射谱显示出4组发射峰,其主发射峰位于620nm,对应Eu3+的5D0→7F2跃迁;Eu3+掺杂摩尔分数为2%时,Ba3Tb(BO3)3:Eu3+发光亮度最高。经分析发现Ba3Tb(BO3)3:Eu3+存在Tb3+→Eu3+的能量传递。  相似文献   

13.
Ternary 0.552Pb(Ni1/3Nb2/3)O3-xPbZrO3-(0.448-x)PbTiO3 (PNN-PZ-PT) ceramics near the triple point compositions were fabricated by an improved two-step sintering method. The triple point composition 0.552PNN-0.135PZ-0.313PT ceramic has outstanding piezoelectric performance with piezoelectric coefficient d33 = 1200 pC/N. Its easy fabrication and low cost make this piezoelectric material an excellent candidate for high sensitivity sensors and ultrasonic transducers. The evolution of domain structures for ceramics with composition near the triple point provides deeper insight into the mechanism of ultrahigh piezoelectric properties of PNN-PZ-PT ceramics.  相似文献   

14.
The piezoelectric strain and resonance performance of 0.37BiScO3-0.6PbTiO3-0.03Pb(Mn1/3Nb2/3)O3 (BS-PT-PMN-xFe) ceramics with different amounts of Fe content addition were investigated from room temperature to 200 °C. Both the piezoelectric strain and resonance performance are improved by Fe addition in wide temperature range. Piezoelectric strain of BS-PT-PMN-xFe with 1 mol% Fe is 0.23%, which is comparable to that of BiScO3-PbTiO3 (BS-PT) ceramics, while the strain hysteresis is only one-third. At 200 °C, the high-field strain coefficient of BS-PT-PMN-Fe with 1 mol% Fe is as large as 700 pm/V. Variation of piezoelectric strain and hysteresis is clearly reducing by Fe addition. The maximum vibration velocity is enhanced up to approximately 1 m/s in 2 mol% Fe-modified BS-PT-PMnN-xFe ceramics, and the vibration velocity is stable from room temperature to 200 °C when the electric voltage magnitude was below 60 Vpp. These results indicate that BS-PT-PMN-xFe ceramics are potential candidates for high-temperature piezoelectric actuator application.  相似文献   

15.
To support photocatalytic decomposition of TiO2 in low‐transparent wastewaters or in the dark, we develop a novel ultraviolet emitting long persistent phosphor CdSiO3:Gd3+,Bi3+, which the persistent luminescence can last for more than 6 h (0.32 mcd/m2). Approximately 68.7% of the spectral areas of the optimal sample can well match the absorption band of TiO2. The long persistent luminescent mechanism is discussed in details. The investigations of decomposition of methylene blue by CdSiO3:Gd3+,Bi3+@TiO2 composite reveals that the long persistent luminescence of CdSiO3:Gd3+,Bi3+ can not only support the photocatalytic activity of TiO2 in the dark but also significantly increases the photocatalytic efficiency under ultraviolet irradiation. Thus, the CdSiO3:Gd3+,Bi3+@TiO2 composite is potentially used as functional photocatalyst to treat the organic pollutants in low‐transparent wastewater or in the dark.  相似文献   

16.
王云杰 《中氮肥》2004,(5):19-20
随着我国农业经济的发展,经济作物种植面积扩大,对无氯钾肥的需求量大幅度增长,全国年需无氯钾肥700kt左右。我国无氯钾肥主要是K2SO4和KNO3,在钾肥中所占比例很小,远不能满足经济作物的需求。我国北方大部分地区干旱缺水,对无氯钾肥需要量更大。目前,我国煤头  相似文献   

17.
掺镨氟化镓铟玻璃的研究   总被引:4,自引:0,他引:4  
合成了一族新的氟化镓铟玻璃,研究了InF3-PbF2-ZnF2-CdF2(BaF2)体系和GaF3-CdF2-PbF2(ZnF2)体系的玻璃形成区域.经玻璃组分试验研究得到了稳定的30PbF2-20GaF3-15InF3-20CdF2-15ZnF2(简化为PGICZ)玻璃,通过优化细调组分,可制得14mm厚块玻璃和具有芯皮结构的光纤.红外和Raman光谱研究结果表明:PGICZ玻璃具有较氟锆酸盐(简化为ZBLAN)玻璃更宽的红外透过范围和更低的声子能量.Pr3+掺杂PGICZ玻璃的1G4能级寿命可达210μs,其量子效率为7%,是通常ZBLAN玻璃的一倍,故它是最可能作为掺镨光纤放大器的实用化体系之一.  相似文献   

18.
Five Ba(Co1/3Nb2/3)O3 samples sintered at different temperatures (form 1350 to 1550 °C), one Ba(Mg1/3Ta2/3)O3 and a Ba(Mg1/3Nb2/3)O3 sample were examined by Raman scattering to reveal the correlation of the 1:2 ordered perovskite structure with the microwave properties, such as dielectric constant and Q factors. The Ba(Co1/3Nb2/3)O3 sample sintered at 1400 °C, which possesses the highest microwave Q value and the lowest dielectric constant among five Ba(Co1/3Nb2/3)O3 samples, has the narrowest width and the highest frequency of the stretch mode of oxygen octahedron (i.e. A1g(O) near 800 cm−1). We found that the dielectric constant is strongly correlated with the Raman shift of A1g(O) stretch modes, and the width of A1g(O) stretch mode reflects the quality factor Q × f value in the 1:2 ordered perovskite materials. This concludes that the oxygen octahedron play an important role of the material's microwave performance. Based on the results of Q × f values and the lineshapes of A1g(O) stretch mode, we found that the propagation of microwave energy in Ba(Mg1/3Ta2/3)O3 and Ba(Mg1/3Nb2/3)O3 shows weak damping behavior, however, Ba(Co1/3Nb2/3)O3 samples sintered at different temperature exhibit heavily damped behavior.  相似文献   

19.
The treatment of cobalt phthalocyanine-3, 3′, 3″, 3′″-tetrasulphonylchloride with different primary amines with different substituents has given eight novel cobalt phthalocyanine-3, 3′, 3″, 3′″-tetrasulphonamide compounds. The structure determination have been carried out using elemental analysis, molecular weight measurements and infra-red spectroscopy. Direct application of the new synthesised dyes to cotton and viscose fabrics at two different bath concentrations gave a range of percentage reflectances values in the visible region. The absorption maxima appeared in both cases in the range 670–680 nm.  相似文献   

20.
Electron-doped SrTiO3 has been attracting attention as oxide thermoelectric materials, which can convert wasted heat into electricity. The power factor of the electron-doped SrTiO3, including SrTiO3-LaTiO3 and SrTiO3-SrNbO3 solid solutions, has been clarified. However, their thermal conductivity (κ) has not been clearly identified thus far. Only a high κ (>12 W m−1 K−1) has been assumed from the electron contribution based on Wiedemann–Franz law. Here, we show that the κ of the electron-doped SrTiO3 is lower than the assumed κ, and its highest ZT exceeded 0.1 at room temperature. The κ slightly decreased with the carrier concentration (n) when n is below 4 × 1021 cm−3. In the case of SrTiO3-SrNbO3 solid solutions, an upturn in κ was observed when n exceeds 4 × 1021 cm−3 due to the contribution of conduction electron to the κ. On the other hand, κ decreased in the case of SrTiO3-LaTiO3 solid solutions probably due to the lattice distortion, which scatters both electrons and phonons. The highest ZT was 0.11 around n = 1 × 1021 cm−3. These findings would be useful for the future design of electron-doped SrTiO3-based thermoelectric materials.  相似文献   

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