Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
  • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
  • C04B35/465—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates
  • C04B35/468—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates
  • C04B35/4682—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates based on BaTiO3 perovskite phase

Definitions

• the present invention relates to another group of bodies whose usefulness is equally widespread.
• This novel group of ceramic compositions have properties such as to make them useful as capacitors in radio, television, and communications generally, as capacitative temperature compensating devices in receivers and communication equipment to prevent distortions due to changes in circuit characteristics caused by temperature changes.
• the dielectric constant of some of these compositions are so high as to make possible their utilization in low frequency distribution and communication systems such as 60 cycle lines, by means of capacitative coupling between a low frequency high tension transmission line and communication telephone lines. Further, these high constants enable these materials to be used as substitutes for high capacity paper and electrolytic type condensers for by-pass, filter, and power circuits, for use in radio, fluorescent lighting circuits, etc.
• the very high dielectric constants make possible the use of these materials as electromechanical devices, for example, the transfer of mechanical energy or motion into electrical energy or vice versa, in a fashion similar to the action exhibited by piezoelectric crystals.
• the novel compositions of the present invention have possible utility in pyroelectricity, supersonics, crystal or condenser microphones, frequency stabilizers, loud speakers, phonograph pickups, telephone design, and oscillator designs generally.
• the foregoing remarks apply particularly to those bodies whose dielectric constants are over 1000 at radio frequency.
• condenser microphones very thin sheets of the higher dielectric constant materials are rigidly clamped at either center or edges and used as vibrating diaphragms. The minute changes of dimension or position of the dielectric due to vibration will occasion relatively large changes in capacity by means of which sound is transformed into electrical energy.
• novel compositions consist broadly of fired mixtures of the titanates of the alkaline earths with the zirconates of the alkaline earths. Mixtures of alkaline earth titanates, stannates, and zirconates are also of utility.
• the alkaline earth compounds generally are of utility for this invention, including those of magnesium, calcium, strontium and barium.
• the peculiarly beneficial effect of the zirconate additions is most strikingly shown in the case of additions to BaTiO'a.
• barium titanate has a dielectric constant of 1200-1300, and a temperature coefiicient which is first negative, then strongly positive, and finally strongly negative between 20 and C. Not only may this erratic behavior be eliminated by addition of the zirconates to barium titanate but dielectric constants of the order of several thousand are common.
• the ingredients as indicated in the table below are properly reacted ceramically and then ground so that the coarsest particles will pass a 325 mesh screen.
• the dried powders are then mixed within the limits indicated by the proportions given in the table. Approximately 10% water is added and thoroughly mixed in the damp powder, granulated by passage through a 20 mesh screen. They are then pressed in a die under a pressure of 5 to 10 tons per square inch, and then allowed to air dry for 24 hours.
• the pieces used for the purposes of this specification are roughly 1 inch in diameter and 0.1 inch thick. Pieces of such size are fired-on a schedule of 400 F.
• the maturation temperature !or all the bodies listed below is between 2450' F. and 2500' 1''.
• the opposing parallel surfaces are painted with silver powder paste w fixed as a silver electrode by firing to 1500' F.
• the values obtained below were determined at one megacycle, using a radio frequency bridge of standard design. Resistivity was determined on a high sensitivity resistance circuit on which a resistance oi a million megohms could easily be detected, the :rero point indicator being a galvanometer.
• the 1000 cycle measurements were obtained through use or an impedance bridge of standard design, whose arms were resistive components.
• the temperature coefllcients of the compositions listed are indicative of the scope of varia- Whlle single compositions may yield the desired coemcient, an infinite variety of coeillcient is possible through parallel combination of one or more bodies.
• a dielectric composition substantially consisting of barium titanate and an alkaline earth zirconate, the latter being present in an amount less than parts for each 100 parts of the iormer combined ceramically whereby the dielectric properties of barium titanate are regulated.
• a dielectric composition substantially consisting of barium titanate and calcium zirconate,
• the latter being present in an amount less than 20 parts for each 100 parts or the former combined ceramically whereby the dielectric properties of barium titanate are regulated.
• Power iactor percent 3 A dielectric composition substantially consisting oi barium titanate and strontium zirconate, the latter being present in an amount less than 20 parts for each 100 parts of the former combined ceramically whereby the dielectric properties of barium titanate are regulated. do 4. A dielectric composition substantially consisting of barium titanate and barium zirconate, the latter being present in an amount less than 20 parts for each 100 parts oi the former combined ceramically whereby the dielectric properties of barium titanate are regulated.
• the method of regulating the dielectric properties 0! barium titanate which comprises combining barium titanate ceramically with a 12222l2200000000ll2224a minor amount of an alkaline earth metal zinconate.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Insulating Materials (AREA)
• Compositions Of Oxide Ceramics (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24023890

Family Applications (1)

Country Status (2)

Cited By (18)

Families Citing this family (6)

Family Cites Families (1)

• 1943
  • 1943-11-02 US US508743A patent/US2402516A/en not_active Expired - Lifetime
• 1951
  • 1951-03-14 DE DEN3613A patent/DE909816C/de not_active Expired

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