水下声成像PVDF—DMOS换能器

本文通过研制水下声成像PVDF-DMOS集成接收换能器,分析了高分子压电薄膜在水声中应用的新途径及其组成换能器的振动模式,建立了机电等效电路图.并分析了影响器件灵敏度的诸因素.介绍了本工作的测量结果,评价了器件的特性.本文可供设计各种PPDF压电换能器、传感器时参考.     

低压微位移驱动电路及控制方法

讨论了低压微位移驱动电路及控制方法在光电轮廓仪上的运用。采用低压驱动电路驱动压电陶瓷相移器对参考光束进行相移，从而使仪器质量减轻、体积缩小、成本降低。在运用该电路时，为了解决压电陶瓷低电压区非线性误差大的问题，用PC计算机控制压电陶瓷上所加电压的电压值，由摄像头摄取图像并计算出干涉条纹的间隔，然后由PC计算机修改压电陶瓷上所加的电压值，直至干涉条纹相位差达到要求值。该方法的优点是：可消除压电陶瓷低压区的非线性误差，使得开环电路得到闭环的效果；可降低机械零部件的装配难度。     

柔性铰链微位移机构在可调谐F-P滤波器中的应用研究

分析了由于反射镜倾斜导致的可调谐F-P(Fabry-Perot)滤波器失谐。设计了一种柔性铰链式微位移机构,由压电陶瓷驱动,采用平行四连杆机构进行传动导向。采用该机构驱动F-P腔镜扫描克服了直接使用压电陶瓷带来的腔镜倾斜问题。该机构已应用于可调谐F-P滤波器中,输出信号多周期峰值幅度均匀,重复性好。     

Phase Transition and High Piezoactivity of Sb Doped （Na0.53K0.435Li0.035）Nb0.94Ta0.06 O3 Lead-Free Ceramics

Lead-free piezoelectric ceramics with the composition of （Na0.53K0.435Li0.035）Nb0.94Ta0.06 O3 （NKLNST） axe synthesized by a conventional solid-state sintering process. An MPB-like region between orthorhombic and pseudocubic phases is found in this system. The density, piezoelectric and dielectric properties axe enhanced greatly in this region. A composition （Na0.53K0.435Li0.035）（Nb0.94Ta0.06）O3 is found to have excellent electrical properties： d33 = 320pC/N, kp= 49% and kt =43%, as well as relatively low loss, tan δ=4.2%, and high relative density higher than 96%, which indicate that this ceramics is a promising lead-free piezoceramics replacing for lead zirconate titanate.     

Indentation Load Effect on Young＇s Modulus and Hardness of Porous Sialon Ceramic by Depth Sensing Indentation Tests

Depth sensing indentation （DSI） tests at the range of 200-1800mN are performed on porous sialon ceramic to determine the indentation load on Young＇s modulus and hardness values. The Young modulus and hardness （Dynamic and Martens） values are deduced by analysing the unloading segments of the DSI test load-displacement curves using the Oliver-Pharr method. It is found that Young＇s modulus ET, the dynamic hardness HD and the Martens hardness HM exhibit significant indentation load dependences. The values of Young＇s modulus and hardness decrease with the increasing indentation load, as a result of indentation load effect. The experimental hf /hm ratios lower than the critical value 0.7, with hm being the maximum penetration depth during loading and hf the final unloading depth, indicate that our sample shows the work hardening behaviour.     

高压烧结法合成致密纳米BaTiO3陶瓷结构和铁电性能研究

 在6 GPa压力、1 000 ℃温度条件下制备了致密的纳米BaTiO₃陶瓷，合成样品的平均晶粒尺寸为50 nm，理论密度在97%以上。通过介电测量，观察到了样品宽化的相变峰，它与粗晶陶瓷的相变峰大不相同。由于90°电畴的减少和退极化场的存在，观察到了细长的电滞回线，它是样品铁电性存在的有力证据，表明钛酸钡陶瓷的临界尺寸在50 nm以下。     

掺Yb3+氧化镧钇透明激光陶瓷的光谱特性

采用传统陶瓷烧结工艺,在无压还原气氛下低温制备出透明性良好的掺Yb3+氧化镧钇透明激光陶瓷,测试了其在室温下的吸收光谱、发射光谱和荧光寿命.结果表明,掺Yb3+氧化镧钇透明激光陶瓷的吸收系数随着Yb3+掺杂浓度的增加而增大,最强吸收峰974nm处的吸收截面为0.90～1.12×10－20 cm2;主发射峰1 032 nm和1 075 nm处的发射截面分别为1.05×10－20 cm2和0.87×10－20 cm2; Yb3+掺杂浓度为5at.%时荧光寿命为1.38 ms,并随Yb3+掺杂浓度的增加而减小;当Yb3+掺杂浓度超过10at.%时,样品中存在严重的浓度猝灭.产生浓度猝灭的原因是高掺杂时离子间存在合作上转换和能量转移.     

Ferroelectric behaviour of 30nm BaTiO3 ceramics prepared by high pressure assisted sintering

Dense nanocrystalline BaTiO3 ceramics with a homogeneous grain size of 30 nm was obtained by pressure assisted sintering. The ferroelectric behaviour of the ceramics was characterized by the dielectric peak at around 120 ℃, the P-E hysteresis loop and some ferroelectric domains. These experimental results indicate that the critical grain size for the disappearance of ferroelectricity in nanocrystalline BaTiO3 ceramics fabricated by pressure assisted sintering is below 30 nm. The ferroelectric property decreasing with decreasing grain size can be explained by the lowered tetragonality and the ＇dilution＇ effect of grain boundaries.     

La2O3对Yb:Y2O3透明陶瓷光谱性能的影响

研究了La2O3对Yb:Y2O3透明陶瓷光谱性能的影响,添加适量La2O3以后,Yb:Y2O3透明陶瓷的吸收峰和发射峰的位置不变,但由于La3+的离子半径大于Y3+的离子半径,在Y2O3中引入La3+离子后,导致Y2O3晶格常数变大,晶场强度变弱,同时降低了Y2O3晶体的有序度,致使发射峰强度有所下降,发射截面变小.过量的La2O3(x=0.16)造成Yb3+激活离子发射强度明显下降;其荧光寿命在添加La2O3后总体增大45%-60%.     

燃烧合成碳化钛微粉的分级

选用两种不同分选剂对燃烧合成的ＴｉＣ微粉进行分级，获得了满足国家标准的磨料粉，比较两种分选剂的分级效率和分级产品质量，表明用聚经物及其添加剂作为ＴｉＣ微粉分选剂的分级效率和分级质量比用树胶分选剂更为优越。当聚氧化物及其添加剂分选液的质量浓度在０．１％左右时具有较高的分级效率。