First Principle Study on the Electronic Structure of Borides

This study utilizes accurate first principle method to conduct a comparative study on he electronic structure of multiple borides. State density of the borides is also summarized. It is found that lanthanum boride has special electronic structure characteristics. Therefore, it is presumed that there is high superconducting transition temperature (Tc) in lanthanum boride. This study is able to provide asignificant theoretical reference for further experimental research.

Experimental Study of Lanthanum Boride Ceramic Powder Synthesis Process

In this paper, the physical and chemical properties of LaB6 Ceramics are introduced, the influence of fabrication techniques on the microstructure and properties of LaB6 Ceramics are discussed. The combustion synthesis process was considered as the proper method for fabrication of LaB6 Ceramic powder with high purity. The results showed that the control additive has a great influence on the synthesis processand the nanoLaB6 Ceramic powder with high purity can be produced made when the content of the control additive is 30%.

THE INFLUENCE OF SPUTTERING BIAS-VOLTAGE ON LaB6 FILM'S CHARACTERISTICS

The deposition of lanthanum boride ( LaB 6) thin films by the DC magnetron sputtering were studied. XRD, AFM and Stylus Profiler were used to characterize the properties of the deposited films. The XRD was used to study the crystallinity. The results of the XRD showed that the dominant crystal face is the (100) face. The crystallinity decreased with the increased bias-voltage value, but the influence of bias-voltage on the films is different on different crystal faces. The intensity (100) face was influenced by the bias-voltage more obviously than other faces except the influence of thickness. The diffraction peak maximal intensity of the (100) face changed from 1256 (on 0 V) to 580 (on -150 V), but the intensity of (110) face changed from 614 (on 0 V) to 486 (on -150 V). The rel. int (100%) of the (110) face changed from 38.70 to 74.52. The deposition rate decreased with the increased bias-voltage value, but the decrease was not obvious. The maximum and minimum of the deposition ratio were 17.53 nm and 13.75 nm respectively. Surface morphology of the films was studied by the AFM. The crystallite of the films was less than 50 nm. The maximal roughness of the films decreased first and increased afterward, and the maximum was obtained on the -50 V bias-voltage.

THE INFLUENCE OF SPUTTERING BIAS-VOLTAGE ON LaB6 FILM'S CHARACTERISTICS

The deposition of lanthanum boride ( LaB 6) thin films by the d.c. magnetron sputtering were studied. XRD, AFM and Stylus Profiler were used to characterize the properties of the deposited films. The XRD was used to study the crystallinity. The results of the XRD showed that the dominant crystal face is (100) face. The crystallinity decreased with the increased bias-voltage value, but the influence of bias-voltage on the films is different on different crystal face. The intensity (100) face was influenced by the bias-voltage more obviously than other faces except the influence of thickness. The diffraction peak maximal intensity of (100) face changed from 1256(on 0V) to 580(on -150V), but the intensity of (110) face changed from 614(on 0V) to 486(on -150V). The rel. int(100%) of (110) face changed from 38.70 to 74.52. The deposition rate decreased with the increased bias-voltage value, but the decreased was not obviously. The maximum and minimum of the deposition ratio were 17.53nm and 13.75nm respectively. Surface morphology of the films was studied by the AFM. The crystallite of the films was less than 50nm. The maximal roughness of the films decreased firstly and increased afterward, and it got the maximum on the -50V bias-voltage.

Ceramic Resistors and Capacitors Embedded in Organic Printed Wiring Boards

Combining thick-film and printed wiring board processes allows thick-film ceramic resistors and capacitors to be embedded in printed wiring boards (PWB). The resistor materials are based on lanthanum boride and cover the range of 10 ohm/square to 10 Kohm/square resistivities. The capacitor material is based on doped barium titanate. Both systems are designed to be “thick-film” printed on copper foil in the locations desired in the circuit and the foil is then fired in nitrogen at 900°C to form the ceramic component on the copper foil. The foil is then laminated, component face down, to FR4 using standard prepreg. The inner layer is then etched to reveal the components in a FR4 matrix. The resistors can be trimmed to tight tolerance at this stage and the components tested. The inner layer can then be laminated into a multilayer PWB. The process is described and the influence of board design, PWB processing and materials are presented and discussed. Examples of circuits using embedded thick-film passives are shown and results of reliability studies are presented.