Microwave dielectric dispersion in RbD2PO4 crystals

The paper presents the results of the investigation of the dielectric dispersion in RbD₂PO₄ in the vicinity of the low-temperature ferroelectric phase transition. It is shown that the dielectric dispersion of Debye type along the b-axis in frequency range 50 MHz to 50 GHz is caused by the single relaxational soft mode which at T_c2=324 K softens to 0.4 GHz. The results confirm the quasi-one-dimensional nature and the order-disorder type of the ferroelectric phase transition.     

The study of domain walls in Pb3(PO4)2 ferroelastic crystals

A ferroelastic domain between two domain walls do not have arbitrary thickness. There can be a minimum thickness which satisfies the geometrical boundary condition. In our study we suggest the possible minimum thickness of domain between two domain walls. The calculated thickness is compared with the observed thickness by TEM.     

如何检验假冒磷酸二氢钾

分析了假冒磷酸二氢钾的特点 ,认为应该选择磷酸二氢钾含量和氧化钾含量做为进货验收时的主检项目 ,必要时可加上氯含量     

Dielectric properties and X-T phase diagram of mixed K1-x (NH4)xH2PO4 crystals

The x-T phase diagram of K_1-x (NH₄)_xH₂PO₄ mixed crystals have been plotted on the base of results of dielectric measurements and literature data.     

KH2PO4-KCl-H2O、NH4H2PO4-NH4Cl-H2O三元体系283.15 K相平衡研究

采用等温溶解平衡法研究了三元体系KH₂PO₄-KCl-H₂O、NH₄H₂PO₄-NH₄Cl-H₂O在283.15 K时的相平衡,并用湿渣法与X射线衍射相结合的方法鉴定了平衡固相的组成与结构。结果表明,三元体系KH₂PO₄-KCl-H₂O和NH₄H₂PO₄-NH₄Cl-H₂O为简单共饱和型,无固溶体或加合物形成,每个相图包含1个不变点、2条单变量曲线和3个结晶区。运用Pitzer电解质溶液理论计算了简单三元体系KH₂PO₄-KCl-H₂O、NH₄H₂PO₄-NH₄Cl-H₂O的饱和溶解度数据,结果表明,KH₂PO₄-KCl-H₂O体系的相对平均偏差为0.046,均方根偏差为0.29,NH₄H₂PO₄-NH₄Cl-H₂O体系的相对平均偏差为0.044,均方根偏差为0.31,溶解度理论计算结果与实验值基本一致。     

磷酸二氢钾的制备工艺

简要论述了磷酸二氢钾的各种制备方法 ,并认为采用湿法磷酸及氯化钾取代热法磷酸和钾碱制备磷酸二氢钾是有利的     

Synthesis and electrochemical properties of monoclinic Li3V2(PO4)3/C composite cathode material prepared from a sucrose-containing precursor

Monoclinic structure Li₃V₂(PO₄)₃/C composite powders are synthesized via a novel homogeneous mixing route followed by a one-step heat treatment. The composites were characterized by X-ray diffraction (XRD) and galvanostatic charge/discharge, CV measurements. The influence of the heat treatment on the electrochemical properties of Li₃V₂(PO₄)₃/C composites was investigated. To examine the effect of residual carbon content on the properties of the composites, six samples with 1.2, 2.3, 3.4, 4.4, 5.8, and 7.0 wt% carbon were prepared. The sample with 4.4 wt% carbon exhibited good cycling performance and rate capability in the range of 3.0–4.8 V.     

283.15 K下三元KCl-NH4Cl-H2O和KH2PO4-NH4H2PO4-H2O体系固-液相平衡测定与关联

采用等温溶解平衡法测定了283.15 K下KCl-NH₄Cl-H₂O和KH₂PO₄-NH₄H₂PO₄-H₂O两个三元体系的溶解度,采用X射线衍射法和湿渣法联合测定平衡固相结构和组成。结果表明,两个体系平衡固相均有部分互溶的固溶体产生,两个相图分别包含一个共饱和点、两条单变量曲线和6个区域。采用Pitzer模型关联和计算两个体系的溶解度数据,结果表明,KCl-NH₄Cl-H₂O体系的最大相对误差为3.096 9%,最小相对误差为0.038 3%,KH₂PO₄-NH₄H₂PO₄-H₂O体系的最大相对误差为5.935 6%,最小相对误差为0.069 8%,模型计算值与实验值基本一致。     

Optical activity and electrogyration of KH2PO4

Accurate measurements of gyration tensors g₁₁ (=-g₂₂) and electrogyration effect of KH₂PO₄ were made by applying the improved HAUP method. g₁₁ diverges conspicuously when the temperature approaches Tc from above and below it, the behaviour being analyzed as obeying the Curie-Weiss law with a Curie-Weiss constant of 7.35×10^-4 K. An electrogyration coefficient π₁₃ referring to the polarization manifests a characteristic nature of improper ferroelectrics.     

Twinning in GLY·H3PO3 crystals

Systematic polarized microscopic observation were done for glycine phosphite crystals along the b-axis. In some as grown crystals natural twinning was found in the (001) plane. Occasionally, appearance of twins in single domain crystals was observed during cracking or polishing of the samples and therefore the crystal can be regarded as at least potentially ferroelastic.     

Studies on the synthesis of sodium ates (NaH2PO4, Na2HPO4, Na3PO4) using membrane electrolysis

Comparative studies have been carried out on the electrosynthesis of sodium phosphates in the cathode compartment of an industrial membrane cell supplied with phosphoric acid of concentrations ranging from 1 to 2 mol dm^–3. The anode compartment of the cell was supplied with brine containing 25% NaCl. Du Pont Nafion^® membranes of types N-423, N-901 and N-961 were used. It was found that current efficiencies for the production of sodium phosphates exceeded 96%, this being higher than that for sodium hydroxide and, in spite of the different properties of the membranes, these efficiencies were similar. With N-423 membrane, the current efficiency was 2 3% lower than that for other membranes, but at the same time, the voltage of the cell was lower by 8 12%. Thus, N-423 membrane gives better performance during sodium phosphate synthesis as compared to membranes N-901 and N-961.     

磷酸一铵中总氮含量的快速测定

用氯化钙作沉淀剂，消除磷酸根离子的干扰，用甲醛法测定磷酸-铵中的总氮，该法简便、快速、准确，加标回收率在98．5％～102．3％。     

Effect of H3PO4 on the PbSO4/PbO2 electrode in H2SO4 solutions

The influence of H₃Po₄ small additions on the polarization behaviour of the PbSO₄/PbO₂ electrode, in H₂SO₄ solutions of different concentrations, was studied using the microelectrode technique and the coulometric method. The reference electrode was the Hg/Hg₂SO₄/H₂SO₄ electrode. The potentiogram analysis and the coulometric measurements show that the main effect of the H₃PO₄ is the drastic passivation of the electrode processes, within the potential range under study, ie the +800 mV to +1650 mV potential range. The Q_a and Q_c electricity amounts are of about 5–10 times smaller in the H₂SO₄ solution with H₃PO₄ addition, compared with the H₂SO₄ solution free of H₃PO₄ addition. A high increase of the oxygen evolution overvoltage could also be seen. Taking into account the ratio between the H₃PO₄ addition amount, in % (w/o) and the PbO₂ active mass per unit surface area, from the lead acid batteries, we can conclude that the small H₃PO₄ additions do not decrease the capacity of the active mass of the battery, but they hinder the insulator film formation between the active mass and the grid.     

快速测定磷酸(氢)钙中磷含量

本方法适合于pH4．2时水溶性的磷酸盐中磷含量的测定、磷酸（氢）钙中磷含量的测定。     

Weak ferroelectricity and low-permittivity microwave dielectric properties of Ba2Zn(1+x)Si2O(7+x) ceramics

Ba₂Zn_(1+x)Si₂O_(7+x) ceramics were prepared using the conventional solid-state method at 1200 °C for 3 h in air. Apart from the previously reported Ba₂Zn_(1+x)Si₂O_(7+x) (x = 0) with a monoclinic structure (C 2/c), the end-member compositions at x = −1 and 1 exhibit single-phase β-BaSiO₃ with an orthorhombic structure (P2₁2₁2₁) and BaZnSiO₄ with a hexagonal structure (P6₃), and possess a coexistence of weak ferroelectricity and low-permittivity microwave dielectric properties. A reduction in Zn²⁺ content mainly decreases the intensity of the ε_r anomaly peak at lower temperature and increases the ε_r (or frequency) stability against temperature. The Zn²⁺-rich BaZnSiO₄ phase has a τ_f value of −181 ppm/°C, whereas the τ_f value of Zn²⁺-free BaSiO₃ phase decreases to −35.4 ppm/°C. The Zn²⁺ deficiency in Ba₂ZnSi₂O₇ composition could inhibit the presence of BaZnSiO₄ phase and improve the τ_f value, whereas excessive Zn²⁺ cations prompt the formation of the BaZnSiO₄ phase to deteriorate significantly the τ_f value.     

Solubility in system CO(NH2)2-NH4NO3-H3PO4-H2O

Solubility data were obtained in the system CO(NH₂)₂-NH₄NO₃-H₃PO₄-H₂O at 0° and 15°C. The results show that high-analysis solution fertilizers can be produced from standard urea-ammonium nitrate (UAN) and phosphoric acid materials. These acidic solution fertilizers contain up to 35% total plant nutrient (TPN = N + P₂O₅ + K₂O), with N:P₂O₅ ratios varying from 20:1 to 1.5:1. Potential liquid products having fertilizer grades of 23-12-0, 26-9-0, 28-6-0, and 31-3-0 are feasible.     

VO(H_2PO_4)_2热分析研究

运用ＴＧ、ＤＴＡ,研究了ＶＯ（Ｈ２ＰＯ４）２在流动空气气氛中的热反应行为、非等温反应动力学和热效应。ＶＯ（Ｈ２ＰＯ４）２从６０９Ｋ开始失重,到６９５Ｋ失重完毕,失重率为１４．０１％,失重后的产物为ＶＯ（ＰＯ３）２。运用Ｓｈａｒｐ法、Ｃｏａｔｓ－Ｒｅｄｆｅｒｎ法和Ｄｏｙｌｅ－Ｚｓａｋｏ法对基础实验数据进行分析,推断出该热分解反应机理为成核和生长（ｎ＝１）,动力学函数为Ａｖｒａｍｉ－Ｅｒｏｆｅｅｖ方程;非等温热分解反应动力学方程：ｄα／ｄＴ＝Ａ／βｅ－Ｅ／ＲＴ（１－α）;动力学补偿方程：ｌｎＡ＝０．１８１Ｅ－４．６８ｂ;热分解反应转变热为０．２９１ｋＪ·ｇ－１。     

NaH2PO4催化合成缩醛(酮)的研究

研究了NaH2PO4催化乙二醇与环己酮、丁酮、丙酮、丙醛、丁醛、异丁醛、戊醛、异戊醛、正己醛、正辛醛、苯甲醛等10余种醛（酮）的缩合反应.考察了反应时间、醛（酮）与醇的配比和NaH2PO4用量等因素对醛（酮）与醇缩合反应的影响.结果表明,当醛（酮）与乙二醇摩尔比为1.0：1.5,催化剂用量为2 g/mol醛（酮）,反应2 h,选择性一般在98%以上,转化率也一般在90%以上.表明,NaH2PO4对醛（酮）与醇的缩合反应有较好的催化性能.     

AlEt3-H2O-H3PO4 catalyzed polymerizations of 1, 4-dioxan-2-one

Summary A new catalytic system, AlEt₃-H₂O-H₃PO₄(C), was successfully used as a catalyst for synthesizing poly (1,4-dioxan-2-one) (PPDO) in bulk via the ring-opening polymerization (ROP) of 1,4-dioxan-2-one (PDO). The effects of the molar ratio of monomer to catalyst (M/C), the polymerization temperature (T), the reaction time (t) and the water content of monomer PDO (W) were studied systematically. AlEt₃-H₂O-H₃PO₄ has been proved to be a very effective catalyst for ROP of PDO. High molecular weights of PPDO can be obtained under following conditions: T=80 °C, M/C=1311–1573, t=8–10 hours and W<80 ppm.     

The peculiarities of isotopic substitution in the RbD3(SeO3)2 crystal

The weakest ferroelectric RbD₃(SeO₃) as distinguished from RbH₃(SeO₃)₂ crystals after lock-in phase transition from incommensurate to commensurate phase has triclinic symmetry has been established. Theoretical-group analysis of this effect has been given.