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Ye X.-S.,Zhejiang University | Wang X.-J.,Zhejiang University | Liang B.,Zhejiang University | Wang Q.,Zhejiang University | And 2 more authors.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2011

To achieve long-term and real-time wireless in-vivo detection of body temperature, a novel passive and wireless telemetering system based on SAW temperature sensor was developed. A radio communication platform based on NI virtual instrument for wireless telemetry was built to test the performance of the sensor. Through this virtual instrument platform, the implantable electronic device, which was composed of 433 MHz SAW temperature sensor and simple resonant circuit, realized the in-vivo temperature monitoring under external 4 MHz electromagnetic energy supply. Results show that the temperature sensitivity of this system is 8.542 kHz/°C at 30~45°C, with the measurement accuracy of ±0.1°C. Furthermore, animal experiment demonstrates that this system has accomplished the measurement of body temperature successfully, and the measuring distance reaches up to 1 m with 20 dBm transmitting power supply.

Yan T.,Shandong University | Yan T.,National Sun Yat - sen University | Leng Y.,Shandong University | Yu Y.,CETC Deqing Huaying Electronics Co. | And 9 more authors.
CrystEngComm | Year: 2014

MgO doped near stoichiometric LiNbO3 (MgOSLN) crystals have great potential for use in periodically poled structured LiNbO3 (PPLN) for doubling frequency lasers and optical parametric oscillation infrared lasers, because of their high optical damage threshold, single domain characteristics, and very low coercive field. However, few MgOSLN crystals are commercially available in the present market because of the great difficulty in growing them. This paper describes how a hanging crucible Czochralski technique with a newly-designed ship lockage type powder feeding system assisted by numerical simulation was developed for the successful growth of high quality near stoichiometric LiNbO3 (SLN) and MgOSLN (~1 mol%) crystals. The physical properties of the crystals were assessed by measuring their crystallinity, Curie temperature, optical properties, coercive field and thermal properties. These properties, including a coercive field of 1.4 kV mm -1 and a thermal conductivity of 6.61 W (m K)-1 demonstrated that the crystals meet the demands for manufacturing periodically poled crystal devices. This growth method has great potential in the mass production of SLN and other incongruently melting crystals. This journal is © the Partner Organisations 2014.

Yan T.,CAS Fujian Institute of Research on the Structure of Matter | Ye N.,CAS Fujian Institute of Research on the Structure of Matter | Xu L.,CAS Fujian Institute of Research on the Structure of Matter | Sang Y.,Shandong University | And 5 more authors.
Journal of Physics D: Applied Physics | Year: 2016

The ferromagnetism of bulk LiNbO3 and LiTaO3 at room temperature was investigated for the first time in the present work. The stoichiometric LiNbO3 is non-magnetic, while congruent LiNbO3 and LiTaO3 show very weak ferromagnetism. After chemical reduction in a mixture of zinc and lithium carbonate powders under flowing nitrogen, the ferromagnetic behavior of each sample became clear, with an increased value of magnetization. The saturation magnetization, the magnetic remanence and the coercive field of reduced congruent LiNbO3 are 7.0 × 10-3 emu g-1, 0.65 × 10-3 emu g-1 and 0.050 kOe, respectively. The ferromagnetism of chemically reduced LiNbO3 and LiTaO3 can be explained by considering the intrinsic Li vacancies, the appearance of Nb4+ (or Ta4+) on the surface with non-zero net spin and the oxygen vacancies at the surface. © 2016 IOP Publishing Ltd.

Yan T.,Shandong University | Liu H.,Shandong University | Wang J.,Shandong University | Zheng F.,Shandong University | And 4 more authors.
Journal of Alloys and Compounds | Year: 2010

Reduced lithium tantalate (LiTaO3, LT) wafers were prepared by chemically reducing regular congruent LT wafers in mixed iron and lithium carbonate powders under a flowing nitrogen atmosphere. The electrical conductivity, Curie temperature, infrared spectrum, UV-vis transmittance, piezoelectric constants and dielectric properties of the LT wafers before and after reduction were measured. In comparison with regular LT wafers, it was found that both the electrical conductivity and the optical absorption in the visible region are greatly increased after reduction, which is beneficial for eliminating pyroelectric discharge and for high accuracy device processing. In addition, we also found that the piezoelectric and dielectric properties of the chemically reduced wafers remain almost the same, a prerequisite for fabricating SAW devices. The effects of mechanisms related to chemical reduction on the evolution of the physical properties of LT wafers are also discussed. © 2010 Elsevier B.V. All rights reserved.

Yan T.,Shandong University | Yan T.,National Sun Yat - sen University | Yu Y.,CETC Deqing Huaying Electronics Co. | Guo Y.,Shandong University | And 7 more authors.
Journal of Alloys and Compounds | Year: 2013

Yb-Mg codoped LiNbO3 (LN) crystals have many applications in self-frequency doubling lasers. However, the great difficulty associated with growing this crystal is one of the obstacles for its application. In this work, Yb-, Mg-doped and Yb-Mg codoped (MgYb0.8 and MgYb1.2) single crystals were successfully grown by the Czochralski method from the congruent melt. Some basic physical properties have been measured to provide reliable reference for application of the crystals. Compared to its value in a singly doped crystal, the effective segregation coefficient of the Yb 3+ ion in codoped crystals clearly decreases. When doping Yb into Mg-doped LN, the absorption edge of the crystal shifts to longer wavelengths, while the refractive index stays nearly the same. Yb3+ doping apparently decreases the Curie temperature Tc. The thermal conductivity of Yb-Mg codoped LiNbO3 was found to be identical to that of Mg-doped LN and greater than that of congruent LN (CLN), which is a benefit for laser applications. The occupation sites of the Yb3+ ions are discussed, and the distinct raised growth ridges observed are attributed to the change in the lattice structure due to Yb-Mg co-doping.© 2013 Elsevier B.V. All rights reserved.

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