Composite oxide capacitor with reverse photosensitive dielectric property and preparation method thereof

Abstract

The invention provides a composite oxide capacitor with a reverse photosensitive dielectric property and a preparation method thereof, and the preparation method comprises the steps: fully mixing 4N high-purity Nb2O5, SnO2 and other reagents, sintering at a high temperature of 1200 DEG C to obtain an Nb2O5-SnO2 composite oxide, and grinding the Nb2O5-SnO2 composite oxide to obtain powder; preparing a cake sample with the diameter of 8mm and the thickness of about 1mm under the pressure of 30MPa, sintering for 12 hours again at 1320 DEG C, and cooling to room temperature. Magnetron sputtering semitransparent Au films are adopted on the two sides of the cake to serve as measuring electrodes. A single-color laser lamp is used as a light source, a single-light-source single-face irradiation mode is adopted, the light intensity of the surface of a sample is adjustable, the maximum light intensity is 200mW / cm < 2 >, and the dielectric constant of 20-106Hz, loss tangent and the like are respectively tested in darkness and various monochromatic light illumination states. The change rates of the optical dielectric constant and the loss tangent are calculated, the optical dielectric constant and the loss tangent are sharply reduced in the low-frequency 20-10000 Hz section, and the maximum change rates can reach 20% and 50%. The characteristics show that the novel composite oxide capacitor has a wide application prospect in the aspects of electronic technology and photoelectric engineering.

Description

Technical Field

[0001] The present invention relates to a composite and a preparation method thereof having excellent photoinduced dielectric response characteristics in the field of electronic materials, and particularly to a composite oxide capacitor with reduced dielectric constant and loss anomaly under light irradiation and a preparation method thereof. Background Art

[0002] A capacitor is an essential electronic component in a circuit, which plays roles such as energy storage, filtering, decoupling, bypassing of AC signals, and AC coupling of AC-DC circuits. It is widely used in various fields such as aviation, aerospace, shipbuilding, weaponry, electronic countermeasures, communication equipment, industrial control equipment, medical electronic equipment, rail transit, precision instrumentation, oil exploration equipment, automotive electronics, laptop computers, digital cameras, mobile phones, audio and video recording equipment, etc. As an important component in a capacitor, the performance of the dielectric material directly determines the quality of the capacitor. At present, electronic devices are increasingly developing towards miniaturization, high integration, and more excellent performance, and there is an urgent need to develop new capacitors with more excellent dielectric properties and capacitors with new properties such as light controllable, sound controllable, and even magnetic controllable. The photocapacitance effect is a type of internal photoelectric effect, which means that when light irradiates the surface of a photosensitive capacitor, the capacitance value will change. A photosensitive capacitor is an optoelectronic device based on the principle of the photoinduced capacitance change effect. By adjusting the capacitance through light irradiation, the capacitance in the circuit can be regulated. Generally, in a semiconductor or insulator photocapacitor, an increase in the carrier concentration under light irradiation will cause an increase in capacitance and a synchronous increase in loss. Summary of the Invention

[0003] The object of the present invention is to provide a composite oxide capacitor (Au / Nb 2 O 5 -SnO 2 / Au) with reverse photosensitive dielectric characteristics and a preparation method thereof. Specifically:

[0004] Step 1: The composite oxide Nb 2 O 5 -SnO 2 samples are synthesized by the high-temperature solid-state reaction method. Using an electronic balance with a precision of 0.0001 g, Nb 2 O 5 (99.99%) and SnO 2 (99.99%) are accurately weighed according to the stoichiometry of the atomic ratio to obtain a mixed oxide with an atomic ratio of Sn:Nb = 1:2.

[0005] Step 2: Place the weighed powders of the two oxides in an agate mortar and grind them manually for about 1 hour to ensure thorough mixing. Then place them in a high-temperature furnace for sintering for 10 hours (sintering temperature: 1200 °C). After that, grind the powder particles to around 800 mesh under the same conditions again and sinter them once more. The above grinding and sintering processes are carried out 3 times to enable full reaction.

[0006] Step 3: Finally, grind the fired compound again, the same as in Step 2. Weigh a certain weight of the powder and put it into a tablet press mold, and make a sample by pressing with a tablet press to prepare a round tablet with a diameter of 8.0 mm and a thickness of about 1.0 - 1.1 mm. Sinter it in the furnace at 1320 °C for 12 hours again, and then cool it at a rate of 3 °C per minute. After sintering, a round tablet is obtained.

[0007] Step 4: At a commercial analysis and testing center, use an X-ray diffractometer to characterize the crystal structure of the prepared sample round tablet; use a scanning electron microscope to detect the surface morphology and microstructure of the sample round tablet.

[0008] Step 5: Magnetron sputter a semi-transparent gold film with a thickness of about 30 nm on both sides of the sample round tablet as measurement electrodes. Bond the two electrodes with silver paste and connect the leads to the lead electrodes of the impedance analyzer 6500B respectively. Set parameters such as dielectric constant, loss, and frequency, and detect the correlation between the dielectric constant and dielectric loss of the sample round tablet and frequency. The test frequency range is from 20 Hz to 1 MHz, and the detection temperature is room temperature. The detection can be carried out separately under dark and light conditions. The light sources are lasers with wavelengths of 405 nm, 450 nm, 520 nm, and 660 nm respectively. Control the on / off of the light source and the adjustment of the light intensity through a switch.

[0009] The advantages and beneficial effects of the present invention are as follows:

[0010] In existing photo-responsive semiconductor or insulator photoelectric capacitors, the carrier concentration increases under light illumination, thereby causing an increase in capacitance and a synchronous increase in loss (positive change). In the composite oxide capacitor (Au / Nb 2 O 5 -SnO 2 / Au) of the present invention, the dielectric constant can be reduced by more than 20% in the low-frequency band under the action of light with a wavelength of 405 nm, and also by more than 10% under conventional visible light. Moreover, both the dielectric loss and capacitance decrease (reverse change), making it an ideal and practical material for photo-controllable capacitors. In this experiment, obvious phenomena occur under conventional visible light, and the higher the frequency energy of the light, the more obvious the phenomena. Description of the Drawings

[0011] Figure 1 is Nb 2 O 5 -SnO 2X-ray diffraction pattern of the composite oxide.

[0012] Figure 2 is Nb 2 O 5 -SnO 2 Scanning electron microscope morphology of the surface of the composite oxide sample.

[0013] Figure 3 is a schematic diagram of the sample electrode and the light irradiation experiment.

[0014] Figure 4 is the change of the dielectric constant with frequency (20 - 10 6 Hz) under dark and monochromatic light irradiation at 405 nm, 450 nm, 520 nm, and 660 nm.

[0015] Figure 5 is the change of the dielectric constant with frequency (20 - 10 6 Hz) under dark and monochromatic light irradiation at 405 nm, 450 nm, 520 nm, and 660 nm.

[0016] Figure 6 is the change of the loss tangent with frequency (20 - 10 6 Hz) under dark and monochromatic light irradiation at 405 nm, 450 nm, 520 nm, and 660 nm.

[0017] Figure 7 is the change of the loss tangent with frequency (20 - 10 6 Hz) under dark and monochromatic light irradiation at 405 nm, 450 nm, 520 nm, and 660 nm. Specific implementation mode

[0018] To make the purpose, technical solution and advantages of the present invention clearer and more understandable, the present invention will be further described in detail in combination with the accompanying drawings and technical solutions.

[0019] According to different stoichiometries, use an electronic balance with an accuracy of 0.0001 g to accurately weigh two reagents of 99.99% high-purity niobium oxide and tin oxide according to the atomic ratio chemical dosage, and use high-temperature sintering to produce Nb 2 O 5 -SnO 2 composite oxide samples;

[0020] Sinter three times in a cycle to prepare Nb 2 O 5 -SnO 2 composite oxide powder, take an appropriate amount of the powder and press it into a disc sample with a diameter of 8 mm and a thickness of about 1 mm under a pressure of 30 MPa, and sinter it again at 1320 °C for 12 hours, and then cool it to room temperature.

[0021] Figure 1 is an X-ray diffraction pattern, indicating it is Nb 2 O 5 -SnO 2 composite oxide. Figure 2 is a scanning electron microscopy surface morphology image, indicating that the surface of the prepared sample wafer is dense and consists of two distinct types of grains. The large grains have a size between 5 and 9 microns, and the small grains are less than 1 micron.

[0022] Magnetron sputtered semi-transparent gold films are used as measurement electrodes on both sides of the wafer, aluminum wires are bonded with silver paste, and the light source is placed on one side of the sample, as Figure 3 shown. Monochromatic light is used as the light source, with a single-source single-sided illumination method. The light intensity on the sample surface is adjustable, with a maximum of 200 mW / cm 2 (reaching the surface of the gold electrode).

[0023] The dielectric constant is measured as a function of frequency in the dark and under illumination, with a frequency range of 20 to 10 6 Hz. Figure 4 is the variation of the dielectric constant as a function of frequency at 20 to 10 6 Hz in the dark and under illumination. In the measured frequency range, the dielectric constant decreases rapidly with frequency in both the dark and under illumination, and the change is more significant at lower frequencies. In the low-frequency range, the dielectric constant under illumination is significantly smaller than that in the dark. Figure 5 is the rate of change of the dielectric constant as a function of frequency at 20 to 10 6 Hz in the dark and under illumination. The rate of change caused by illumination is greater at lower frequencies. Calculate the rate of change of the optical dielectric constant (ε′ 光 -ε′ 黑 ) / ε′ 黑 , which exceeds -20% at most.

[0024] The loss tangent is measured as a function of frequency in the dark and under illumination, with a frequency range of 20 to 10 6 Hz. Figure 6 is the variation of the loss tangent as a function of frequency at 20 to 10 6 Hz in the dark and under illumination. In the measured frequency range, the loss tangent decreases rapidly with frequency in both the dark and under illumination, and the change is more significant at lower frequencies. In the low-frequency range, the loss tangent under illumination is significantly smaller than that in the dark. Figure 7 is the rate of change of the loss tangent as a function of frequency at 20 to 10 6 Hz in the dark and under illumination. The rate of change caused by illumination is greater at lower frequencies. Calculate the rate of change of the loss tangent (tanδ 光 -tanδ 黑 ) / tanδ 黑 , which exceeds -50% at most.

Claims

1. A method for preparing a composite oxide capacitor with reverse photosensitive dielectric properties, characterized in that: The steps include: Step 1: The composite oxide Nb2O5-SnO2 sample is synthesized by a high temperature solid phase reaction method; an electronic balance with an accuracy of 0.0001g is used to accurately weigh 99.99% high-purity Nb2O5 and SnO2 according to the atomic ratio chemical dosage, thereby obtaining a mixed oxide with an atomic ratio of Sn:Nb=1:2; Step 2: Grind the weighed two oxide powders in an agate mortar to ensure thorough mixing; then sinter in a high-temperature furnace for 10 hours; Step 3: Grind the fired compound again, as in step 2; weigh the powder and put it into a tableting mold, use a tablet press to make a tablet, sinter it in a furnace at 1320°C for 12 hours, and then cool it at 3°C / min; after burning, a disc is obtained.

2. The method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to claim 1, characterized in that: In step 2, choose to grind manually for 1 hour or add anhydrous ethanol and grind in a ball mill for 3 hours.

3. The method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to claim 1, characterized in that: In step 2, the sintering temperature is 1200°C.

4. The method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to claim 1, characterized in that: In step 2, the powder particles are ground to 800 mesh under the same conditions and sintered again. The above grinding and sintering process is carried out 3 times in total to allow for sufficient reaction.

5. The method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to claim 1, characterized in that: In step 3, a disc with a diameter of 8 mm and a thickness of 1.0 to 1.2 mm is prepared.

6. A method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to any one of claims 1 to 5, characterized in that: The crystal structure of the prepared sample disc was characterized by an X-ray diffractometer; the surface morphology and microstructure of the sample disc were detected by a scanning electron microscope.

7. A method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to any one of claims 1 to 5, characterized in that: On both sides of the sample disc, a translucent gold film of about 30 nanometers after magnetron sputtering is used as the measuring electrode. The two electrodes are bonded with wires using silver glue and respectively connected to the lead-out electrodes of the impedance analyzer 6500B. The dielectric constant, loss and frequency parameters are set to detect the correlation between the dielectric constant and dielectric loss of the sample disc and the frequency. The test frequency range is from 20Hz to 1MHz, and the detection temperature is room temperature.

8. The method for preparing a composite oxide capacitor with reverse photosensitive electrical characteristics according to claim 7, characterized in that: The detection was conducted in dark and light conditions respectively. The monochromatic light sources were lasers with wavelengths of 405nm, 450nm, 520nm, and 660nm. The light source was turned on and off by a switch to adjust the light intensity.

9. A composite oxide capacitor with reverse photosensitive electrical characteristics, characterized in that: The material is prepared by the preparation method as claimed in claim 1, and the chemical formula is: Au / Nb2O5-SnO2 / Au.

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