复相陶瓷(0.5BaO0.5SrO)[(1-y)TiO2yNb2O5]的介电性能研究

通过对组成进行一定的过量控制，利用传统陶瓷工艺，成功制备了具有钙钛矿相钛酸锶钡固溶体和钨青铜相铌酸锶钡固溶体两相稳定共存的(0.5BaO0.5SrO)[(1-y)TiO2yNb2O5](BSTN)复相陶瓷.用Riguaku D/max-2400型X射线衍射仪和KEITHLEY 3330阻抗分析仪对所得样品的相结构状态及介电性能进行了测试.结果表明：Y值在0.1～0.7之间的BSTN复相陶瓷为钙钛矿相和钨青铜相两相稳定共存的复合相；在该范围以外，则为单一相的钛酸锶钡与Nb或铌酸锶钡与Ti的固溶体.复相陶瓷的介电性能取决于钙钛矿相和钨青铜相的相对含量及其固溶度，当组成y约为0.7时，介电常数达到最大值；随测试频率的提高，介电常数和损耗降低.复相陶瓷中钨青铜相的铁电/顺电相转变温度与钨青铜相中固溶TiO2量相关，随固溶量增加，转变温度降低.同时，受复相陶瓷中钙钛矿相的影响，随钙钛矿相相对含量的增加，转变温度升高；钨青铜相的最低铁电/顺电相转变温度出现在约110℃，比Sr0.5Ba0.5Nb2O6下降约240℃.     

Crystal Structure and Dielectric Properites of Bao.6Sr0.4TiO3/MgO Ceramics Doped with ZrO2 and MnO2

通过固相反应法制备Mn、Zr共掺杂钛酸锶钡／氧化镁陶瓷粉体,经干压成型后在空气气氛中于l450℃烧结4h,通过扫描电子显微镜和X射线衍射研究了ZrO2和MnO2共掺杂的Bao6Sro4TiO3／MgO复合陶瓷材料的微结构和介电性能。结果表明：Zr02可以显著降低材料的介电常数和介电损耗,有效提高了陶瓷材料的温度稳定性;随ZrO2添加量的增加,体系的晶胞参数略有增加,MgO在钛酸锶钡中以独立相的形式存在：制备出的BST铁电陶瓷材料的25℃相对介电常数较低（＆〈110）,介质损耗小于1．0×10^-3（在频率为10kHz时）,温度系数小于6．012×10^-3,可调性大于20％（8．0kV／mm）,适用于制作移相器。     

炭吸附硼酸锶纳米粉体的制备及其光催化性能研究

采用炭吸附沉淀法,以氯化锶、五硼酸铵为原料,制备了硼酸锶纳米催化剂。利用热重/差热分析仪（TG-DTA）、X射线衍射仪（XRD）、透射电镜（TEM）和紫外可见光谱仪（UV-Vis）等对所得催化剂的焙烧温度、物相、微粒尺寸及光吸收性能进行表征。结果表明：炭黑的吸附有效阻止了纳米硼酸锶催化剂在制备过程中的团聚和烧结, 600 ℃下焙烧的纳米硼酸锶粉体具有良好的分散状态,平均晶粒尺寸为13 nm,比表面积为83.26 m2/g。罗丹明B紫外光催化反应结果表明,在60 min内罗丹明B在硼酸锶催化剂上几乎完全分解。     

Suppression of Liquid Film Migration and Improvement of Dielectric Properties in Niobium-Doped Strontium Titanate

In an attempt to improve the dielectric properties of SrTiO₃-based boundary-layer capacitors (BLCs), the effects of infiltrant composition on the liquid film migration and dielectric properties in 0.2-mol%-Nb₂O₅-doped SrTiO₃ were investigated. Powder compacts were sintered at 1480°C for 5 h in 5H₂·95N₂ and infiltrated with 80Bi₂O₃·20( x CaO–(1 – x )BaO) at 1300°C for various times in air. When the value of x was 0, 0.2, 0.7, and 1.0, liquid film migration occurred, which formed a new solid-solution layer containing solute species. On the other hand, when x = 0.5, no liquid film migration was observed. The effective dielectric constant was the highest in the sample with x = 0.5 (no liquid film migration), and it decreased as the migration distance increased. In addition, the loss tangent was the lowest, <1%, in the sample with x = 0.5. Agreement between the estimated effective dielectric constants and the measured values showed that the suppression of liquid film migration improved the dielectric constant. The agreement further indicated that the prediction of the dielectric constant in SrTiO₃-based BLCs was possible using a two-layer model with a liquid-infiltrated layer and a SrTiO₃-based oxidized layer.     

碳酸锶废渣酸浸尾气的处理研究

将酸浸碳酸锶废渣时逸出的硫化氢气体和空气通入硝酸铁溶液中,硫化氢被氧化得到硫磺,硝酸铁溶液可重复使用。通过实验研究确定了较优实验条件：硝酸铁浓度为0.5 mol/L,实验温度为30 ℃,所得硫磺纯度为99.38%,每得到1 g硫磺时硝酸铁损失量（以Fe₂O₃计）为0.013 7 g。该方法具有条件容易控制、工艺流程简单等优点,适用于碳酸锶废渣酸浸过程中硫化氢气体的处理。     

晶格畸变对锶铁氧体粉末永磁性能的影响

锶铁氧体预烧料经高能球磨制成磁粉,对不同温度处理的系列磁粉进行磁性检测和X射线衍射(XRD)分析.结果表明,球磨后再退火处理的磁粉内禀矫顽力大幅提高:球磨时间越长,退火后的内禀矫顽力越高.退火后磁粉有-Fe2O3出现,相同退火温度,研磨时间越长,Fe2O3相含量越多.磁粉平均粒度相同时,晶格畸变越小,磁粉内禀矫顽力越大;反之亦然.     

雷尼酸锶的合成

以柠檬酸为原料,经过脱羧、酯化、环合、烷基化、水解和成盐反应制得雷尼酸锶,总收率为58.6%。改进后的工艺反应条件温和、操作简单,适合于工业化生产。     

The Effect of Polybutylcyanoacrylate Nanoparticles as a Protos Delivery Vehicle on Dental Bone Formation

Background: Dental implants are commonly used for missing teeth, for which success depends heavily on the quality of the alveolar bone. The creation of an ideal implant site is a key component in shortening the treatment time, which remains clinically challenging. Strontium ranelate (Protos) is an anti-osteoporotic agent which has previously been used to promote bone formation, however the systemic use of Protos has been linked to serious cardiovascular and venous thromboembolic events, thus local delivery strategies may be better suited for this purpose. In this study, a biodegradable, and biocompatible nanocarrier “polybutylcyanoacrylate” (PBCA) loaded with strontium was constructed and its ability to promote bone formation was assessed. Methodology: PBCA nanoparticles loaded with strontium (PBCA-Sr NPs) were synthesized using the emulsion polymerization method, and their physical properties (zeta potential, size and shape) and entrapment efficiency were characterized. Committed MSCs (osteoblasts) were derived from the differentiation of cultured rat mesenchymal stem cells (MSC), which were tested with the PBCA-Sr NPs for cytotoxicity, inflammatory response, bone formation and mineralization. Scanning electron microscopy was performed following a 7-day treatment of PBCA-Sr NPs on decellularized procaine mandibular bone blocks grafted with osteoblasts. Results: Spherical PBCA-Sr NPs of 166.7 ± 2.3 nm, zeta potential of −1.15 ± 0.28 mV with a strontium loading efficiency of 90.04 ± 3.27% were constructed. The presence of strontium was confirmed by energy-dispersive X-ray spectroscopy. Rat committed MSCs incubated in PBCA-Sr NPs for 24 hrs showed viabilities in excess of 90% for concentrations of up to 250 ug/mL, the cellular expression of osteocalcin and alkaline phosphatase were 1.4 and 1.3 times higher than the untreated control, and significantly higher than those treated with strontium alone. Bone formation was evident following osteoblast engraftment on the decellularized procaine mandibular bone block with PBCA-Sr NPs, which appeared superior to those treated with strontium alone. Conclusion: Treatment of committed MSCs with PBCA-Sr NPs showed higher expression of markers of bone formation when compared with strontium alone and which corresponded to greater degree of bone formation observed on the 3-dimensinal decellularized procaine mandibular bone block. Further quantitative analysis on the extent of new bone formation is warranted.     

Low thermal conductivity of SrTiO3−LaTiO3 and SrTiO3−SrNbO3 thermoelectric oxide solid solutions

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.     

3D-printed barium strontium titanate-based piezoelectric scaffolds for bone tissue engineering

In order to promote bone healing, new generations of biomaterials are under development. These biomaterials should demonstrate proper biological and mechanical properties preferably similar to the natural bone tissue. In this research, 3D-printed barium strontium titanate (BST)/β-tricalcium phosphate (β-TCP) composite scaffolds have been synthesized as an alternative strategy for bone regeneration to not only induce appropriate bioactive characteristics but also piezoelectric behavior. The physical, chemical and biological performance of the scaffolds have been examined in terms of mechanical, dielectric properties, apatite-forming ability, Alizarin Red Staining (ARS), Alkaline Phosphatase activity (ALP), and cytotoxicity. The samples composed of 60% BST and 40% β-TCP showed the highest compressive strength, bending module, elastic modulus and the Young's modulus. The dielectric constant increased with further addition of the BST phase in the constructs. Scanning Electron Microscope (SEM) and energy dispersive X-ray (EDX) analyses showed that 60% BST/40% β-TCP sample had the highest amount of bone-like apatite formation after 28 days in simulated body fluid (SBF). Moreover, the results of ARS proved that 60% BST/40% β-TCP composite could present higher quantities of mineral deposition. The ALP activity of osteosarcoma cells on 60% BST/40% β-TCP sample showed higher activities compare with the other composites. None of the samples demonstrated any sign of toxicity using MTT test. It can be suggested that BST/β-TCP composite scaffolds can be potentially used as the next generation of bone tissue engineering scaffold materials.