Dielectric Properties of Solid Solutions of Sodium Niobate-Lead Zirconate and Sodium Niobate-Lead Titanate

Solid solutions based on sodium niobate with limited amounts of lead and zirconium or lead and titanium solute ions have been investigated with respect to their dielectric constant versus temperature at 1 kc. per second from −175° to 300°C. Lead zirconate additions to sodium niobate up to 15 mole % cause an increase in dielectric constant, with a value of 1345 at 6°C. being the maximum recorded. Lead titanate additions to sodium niobate cause a general increase in dielectric constant up to 25 mole %, with 675 at 30°C. and 4670 at 154°C. being the maximum values recorded. Polarization versus applied field measurements up to 30,000 volts per cm. show nonreversible polarity for the lead zirconate compositions, whereas the compositions containing from 10 to 50 mole lead titanate are ferroelectric. An induced ferroelectricity phenomenon occurs for the composition containing 5 mole % lead titanate. A remanent polarization of 15 microcoulombs per sq. cm. at a coercive force of 7800 volts per cm. was obtained at room temperature for the composition 0.85 NaNbO₃–0.15 PbTiO₃.     

Electrical Properties of Lead-Barium Niobates and Associated Materials

The electrical properties of materials in the system lead-barium niobate are described. Particularly useful materials are obtained when between 25 and 50 mole % of lead niobate is replaced by barium niobate. Materials with a 40 to 45 mole % replacement have permittivities of more than 1500 and radial electromechanical coupling coefficients of more than 0.35, but the Curie temperature is then only about 250°C, the minimum value obtained in the system. Higher Curie temperatures are accompanied by somewhat lower values of permittivity and coupling coefficient. An indication is given of the effects of several other additives on the properties of lead niobate, and it is shown that barium-strontium niobates are only weakly ferroelectric at room temperature.     

Conventionally Sintered (Na0.5,K0.5)NbO3 with Barium Additions

The effect of Ba additions on sodium potassium niobate (NKN) ceramic bodies was investigated with regard to sintering behavior, densification, and electrical properties. Small additions of Ba retard grain growth and increase density. The approximate solubility limit of Ba is 1.5 mol%. During firing the loss of Na and K was very low. Both electrical phase transitions in NKN are lowered with Ba additions. The Ba-containing bodies show higher permittivity values than hot-pressed materials, while radial coupling and d₃₃ were similar to or higher than those of the conventionally sintered pure materials.     

Dielectric and Structural Investigations of the System BaTiO3-BaHfO3

Dielectric measurements and X-ray diffraction studies were made in the system BaTiO₃-BaHfO₃ for polycrystalline specimens containing from 0 to 30 mole % BaHfO₃. The maximum in the dielectric constant for each composition in creased as the BaHfO₃ concentration was in creased to 16 mole % and then decreased with further BaHfO₃ additions. Room-temperature lattice constants and hysteresis loops were meas ured for all compositions. A partial solid-state phase diagram is suggested for the solid solution area of the system. The phase diagram and the dielectric behavior of the system up to 16 mole % BaHfO₃ are explained on the basis of Devonshire's thermodynamic theory. The ferroelectric-paraelectric transition in the composition containing 16 mole % BaHfO₃ was essentially of second order and occurred between a ferroelectric rhombohedral phase and a paraelectric cubic phase.     

SO2/O2 dehydrogenation of ethylbenzene

In the SO₂ dehydrogenation of ethylbenzene to styrene using alkalized alumina or titania catalysts, addition of small amounts of oxygen results in (1) higher styrene yields at equivalent SO₂ concentrations, or (2) equivalent styrene yields with lower SO₂ requirements. By staging the oxygen additions, styrene yields of greater than 80% are achieved at SO₂ levels as low as 0.15 mole/mole ethylbenzene when 0.45 mole O₂ is added in increments of 0.15 mole. The low SO₂ concentration and staging of the oxygen result in a high selectivity (94%) for the reaction to styrene by minimizing both byproduct formation and combustion.     

Dielectric Bodies in Metal Stannate-Barium Titanate Binary Systems

Ceramic and dielectric properties of bodies in the binary systems of barium titanate plus the stannates of magnesium, lead, bismuth, zinc, nickel, copper, cadmium, cobalt, manganese, and iron have been investigated. Bodies in the system tin oxide-barium titanate also have been evaluated. Additions of tin oxide, lead stannate, cadmium stannate, zinc stannate, and copper stannate progressively decrease the Curie temperature of the body. Lead stannate bodies exhibit somewhat flatter peaks than the others and show much less variation of dielectric constant with temperature than do similar bodies prepared with the stannates of barium, calcium, or strontium. Additions of magnesium stannate, bismuth stannate, and nickel stannate greatly depress the Curie peak of barium titanate bodies. Bismuth stannate is particularly effective in producing bodies with very low temperature coefficient of dielectric constant. Bodies having dielectric constants of 4000 to 5000 (+25%, −50% from −60° to 85°C.) may be obtained from compositions containing about 15 mole % PbSnO₃. Bodies having dielectric constants of 2000 to 2300 (+ 10%, −40% from −60° to 85°C.) may be obtained from compositions containing about 4 or 5 mole% of either MgSnO₃or NiSnO₃. Bodies having dielectric constants of 1000 to 1200 (−4% from −60° to 85°C.) may be obtained from compositions containing about 5 mole % Bi₂(SnO₃)₃. Limited data indicate that the aging of various compositions apparently increases with level of dielectric constant. Non-linearity with d.-c. bias is greatest for high peak-K bodies. Up to the limits investigated, additions of CaSnO₃, PbSnO₃, MgSn0₃, and Bi₂ (SnO₃)₃ are absorbed in BaTiO₃ bodies as solid-solution-type simple cubic structures with slightly expanded lattices.     

Lead-free sodium niobate nanowires with strong piezo-catalysis for dye wastewater degradation

In this work, the hydrothermally-synthesized sodium niobate nanowires were used to decompose Rhodamine B dye solution through the piezo-catalytic effect. With the sodium niobate catalyst, a high piezo-catalytic degradation ratio of ～80% was achieved under the excitation of vibration for the Rhodamine B dye solution (～5?mg/l). These active species in the catalytic process, hydroxyl radicals and superoxide radicals with the strong oxidation ability, were also observed, which confirmed the key role of piezoelectric effect for piezo-catalysis. The piezo-catalysis of sodium niobate nanowires provides a high-efficiency and reusable tool in application in depredating the dye wastewater.     

Dielectric and thermal expansion properties of LHPG grown potassium lithium niobate single crystals

Compositions of potassium lithium niobate K₆Li_4+xNb₁₀O₃₀ (x for excess mole % of Li₂O) with tetragonal tungsten bronze structure were prepared as crystal fibers by the Laser Heated Pedestal Growth technique. The lattice constants of KLN were measured by using X-ray diffraction and typical values for a = 12.5703 ± 0.0018 and c = 3.9485 ± 0.0012 were measured. This paper reports the dielectric permittivity measurements on single crystal along the a- and c- axis in the temperature range of 90-450K and frequency range of 10²-10⁵ Hz. The dielectric permittivity at room temperature along a- and c- axis was 430 and 330 respectively. Mechanism for the low temperature dielectric relaxation will be discussed. Thermal expansion behavier in the a- and the c-direction will also be reported.     

铜铁双掺近化学计量比铌酸锂晶体生长及其光折变性能研究

采用优化工艺参数,在掺有6（mol）％K2O助溶剂熔体中,利用提拉法生长出系列铜、铁双掺近化学计量比LiNbO3晶体。通过二波耦合和透射光斑畸变法测试可知,在未掺和掺铁量不变情况下,随着掺铜量的增加,衍射效率逐渐增大且铜铁双掺铌酸锂晶体衍射效率要高于单掺铜铌酸锂晶体。而其写入时间和擦除时间逐渐减小;抗光损伤能力随着掺铜量的增加逐渐增强,且单掺铜铌酸锂晶体抗光损伤能力远远大于铜铁双掺铌酸锂晶体。     

Dielectric Bodies in the Quaternary System BaTiO3–BaSnO3–SrSnO3–CaSnO3

Dense bodies were prepared of compositions in the quaternary system BaTiO₃–BaSnO₃–SrSnO₃–CaSnO₃ containing from 3 to 60 mole % stannate. The general effect of the stannate addition to barium titanate was to decrease the Curie temperature and broaden the peak. On a molar basis the three stannates were approximately equivalent in their effect on the dielectric properties of barium titanate, although the rate of shift of the Curie temperature was slightly greater when SrSnO₃ was used. Bodies containing calcium or strontium stannate had lower power factors than those containing barium stannate. Bodies compounded with calcium stannate matured most readily and at lower temperatures. Bodies having dielectric constants ( K ) of 2300 to 2800 at 1 kc. with low positive temperature coefficients up to about 55°C. were obtained with a 3 mole % addition of stannate. Bodies with minimum K 's of 3000 to 4000 at 1 kc. over the range 25° to 85°C. were obtained from BaTiO₃ with an addition of about 6 mole % BaSnO₃, SrSnO₃, or CaSnO₃. Bodies with negative temperature coefficients of K ranging from about 13,000 to about 1000 p.p.m. per °C. were obtained with stannate additions of from 10 to 60 mole %.     

Volume Relations in Na2O·B2O3 and Na2O·SiO2 B2O3, Melts at 1300·C

Density (and some viscosity) data are presented for binary sodium borate melts containing as much as 60 mole % Na₂O and for ternary sodium silicoborate melts with B/Si <2.0 between 1000°C and 1300°C. The high-temperature partial molar volume analysis of the binary sodium borate melts reveals about 50% BO₄ tetrahedra at the 40 mole % Na₂O composition, in agreement with recent NMR estimates for the binary glasses. No "boron anomaly" was found near 18 mole % Na₂O at high temperature. The synthetic partial molar volume model that agrees best with experiment for all ternary melts studied involves the presence of some BO₄ tetrahedra, the percentage of which varies with composition. This ternary model involves a high degree of internal consistency. No tendency toward extensive micro-immiscibility was observed for ternary melts near the SiO₂·B₂O₃ binary.     

Effect of Metal Oxide Additions on the High-Temperature Electrical Conductivity of Alumina

Several metal oxide additions were made to typical 99 and 96% alumina compositions to study their effect on the electrical conductivity of alumina from 500° to 1400°C. The metal oxide additions investigated were CO₂O₃, Cr₂O₃, CuO, Fe₂O₃, MnO₂, NiO, and TiO₂. Using a guarded two-probe technique, dc resistivities were measured on nonporous ceramic specimens. Additions of 0.5 to 2 mole % Co₂O₃, 2 mole % CuO, 1 mole % Fe₂O₃, or 2 mole % NiO to either a 96 or a 99% alumina composition increased the electrical resistivity. The addition of 1 mole % Cr₂O₃ to either a 96 or a 99% alumina showed practically no change in the resistivity. All changes in resistivity seemed to be structure dependent.     

Piezoelectric Properties and Phase Relations of Pb(Mg1/3Nb2/3)O3-PbTiO3−PbZrO3 Ceramics with Barium or Strontium Substitutions

When a small amount of Ba or Sr is substituted for Pb in Pb(Mg_1/3 Nb_2/3)O₃-PbTiO₃-Pb2rO 3 , the morphotropic boundary and the compositions which show the highest planar coupling coefficient and dielectric constant shift slightly toward the decreasing PbTiO₃ content. The tetragonality of Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ and Pb(Mg_1/2 Nb_2/3)-O₃-PbTiO₃-PbZrO₃ ceramics decreased with increasing Ba or Sr content. The lattice parameter (α axis) in the rhombohedral or pseudocubic phase increased with the increase of Ba but decreased with the increase of Sr substitution. Although the Curie temperature was lowered with the increase of Ba or Sr, the dielectric constants of the ceramics were increased. The dielectric and piezoelectric properties of the ternary compositions near the morphotropic boundary were improved through selection of sub-stituent and base composition. A planar coupling coefficient of 0.66 and a low Young's modulus were obtained with substitution of 5 mole % Ba. A dielectric constant greater than 3500 and a planar coupling of 0.63 can be obtained by substituting 5 mole % Sr.     

硼酸与5-苯基-四氮唑复合盐的合成

以苯甲腈、叠氮钠等为原料,经偶合,成盐合成了硼酸复合5 苯基四氮唑。研究了反应时间、反应温度对产品收率的影响。实验表明:在n(苯甲腈)∶n(叠氮钠)=1∶1.1,催化剂用量为反应物总量的25%,120℃反应20h可得到收率90%的5 苯基四氮唑。在n(5 苯基四氮唑)∶n(硼酸)=1∶1,120℃反应30min的条件下,可得到约90%的标题化合物。原料经二步反应后的总收率为81%。     

Hydration of Tricalcium Silicate in the Presence of Lignosulfonates, Glucose, and Sodium Gluconate

Two commercial calcium lignosulfonates were separated into their main constituents, i.e. fractions high in salts of lignosulfonic acids and fractions high in sugars and sugar-acid salts. Hydration of C₃S in the presence of these fractions was studied. The fractions high in sugar acids caused a delay in hydration with a subsequent acceleration of hydration at additions of 0.1%. Fractions high in lignosulfonates caused little delay, whereas additions of 0.5% caused complete inhibition. Hydration was also studied in the presence of glucose and sodium gluconate. Adding 0.1 % glucose delayed hydration for about 11 days, whereas adding 0.1% sodium gluconate caused complete inhibition. The delay in hydration is discussed in terms of poisoning of nucleation sites.     

芳香族偶氮化合物三阶非线性光学材料的合成研究

将含有不同取代基的芳胺在0~5℃下与亚硝酸钠和盐酸进行重氮化反应(摩尔比为芳胺∶亚硝酸钠=1∶1.2),制得相应的重氮盐,再分别与苯代三聚氰胺(BGA)(摩尔比为芳胺∶苯代三聚氰胺=1∶0.8)发生偶合反应,最终得到一系列新的含有不同取代基的芳香族偶氮化合物,反应收率为57%~65%。通过红外、紫外、元素分析、核磁对其结构进行了表征。     

Effect of water-soluble and water-insoluble long-chain polar additives on micellar solutions of sodium dodecylbenzene sulfonate

Additions of long-chain polar compounds to aqueous solutions of sodium dodecylbenzene sulfonate resulted in the separation of a liquid-crystalline phase. This was first observed after the addition of 0.2 to 0.25 mole of water-insoluble polar compound per mole of anionic surfactant. It was found necessary to add 0.6 to 2 moles of watersoluble long-chain polar compound per mole of anionic surfactant before a separate liquid-crystalline phase could be observed. At concentrations below that required for liquid-crystal formation, additions of PEG 400 monostearate to aqueous solutions of sodium dodecylbenzene sulfonate resulted in a steady decrease in the Krafft temperature, a viscosity minimum, and a surface-tension minimum. With sucrose monotallowate, similar results were obtained, except that a minimum was not obtained in the viscosity-concentration curve.     

Crystal Chemistry and Dielectric Properties in the Systems BaTiO3-UO2 and BaTiO3-BaUO3

Polycrystalline barium titanate fired in nitrogen at 1300° to 1400°C accommodates up to 3 mole % UO₂ in solid solution; its structure is then cubic at room temperature. With BaUO₃ additions the structure becomes disordered and quasi-cubic. In air, about 1 mole % UO₂ goes into solid solution in BaTiO₃ but the structure remains tetragonal. Diffraction peaks of a new phase, possibly a ternary oxide of barium, uranium, and titanium, appear in patterns of specimens containing more than 2 mole % UO₂. The dielectric constant of BaTiO₃ ceramics fired in air, steam, or oxygen increases with up to about 0.5 mole % UO₂ but declines rapidly above this level. The dielectric constant of BaUO₃ is about two orders of magnitude lower than that of BaTiO₃, and additions of BaUO₃ invariably lower the dielectric constant of BaTiO₃.     

二甲基二烯丙基氯化铵-丙烯酰胺共聚物的合成与结构表征

用二步法合成了季铵盐阳离子单体N ,N 二甲基二烯丙基氯化铵 (DMDAAC)。第一步 ,向反应瓶中加入 1mol二甲胺的水溶液 ,控制温度 40℃以下 ,滴加 1mol氯丙烯和 1molNaOH水溶液 (其质量分数为 40 % )。滴加完后再反应 2h,分取上层有机相 ;第二步 ,将有机相加入反应瓶中 ,同时加入适量的丙酮 ,控制温度在 30℃以下 ,滴加 1mol氯丙烯 ,反应 4h。过滤、洗涤、干燥得阳离子单体DMDAAC ,总转化率为 63%。以n(DMDAAC)∶n(丙烯酸胺 ) =1∶3在水溶液中共聚 ,合成了阳离子共聚物 [P(DMDAAC AM) ]。反应以分别占单体总质量的 0 5 %的过硫酸钾和亚硫酸氢钠为引发剂 ,反应温度 40℃ ,反应时间 6～ 8h。并利用IR、1HNMR对单体和共聚物进行了结构表征。     

Glass Formation and Properties of Glasses in the System Na2O-B2O3-SiO2-TiO2

An investigation was made of the effect of TiO₂ on the glassforming region and on the physical properties of glasses in the system Na₂O-B₂O₃-SiO₂TiO₂. Glasses containing up to 45 mole % TiO₂ may be formed with an alkali content of 30 mole %. At lower alkali contents (10 mole % Na₂O) glasses may be formed containing up to 22 mole % TiO₂. The way in which the coefficient of linear thermal expansion and the transformation and softening temperatures are affected by TiO₂ additions has been determined.