# US 5,351,033 A · Semi-hard magnetic elements and method of making same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,351,033 A - Document ID: US5351033A - Status: Granted - Kind: A - Application number: 07/955,319 - Filed: 1992-10-01 - Granted: 1994-09-27 - Earliest claimed: 1992-10-01 - Assignees: Sensormatic Electronics Corporation - Inventors: Nen-Chin Liu; Robert C. O'Handley; Wing Ho; Richard Copeland - Web page: https://patentgrep.com/patent/US5351033A ## CPC - G08B 13/2411: {Tag deactivation} - G01V 15/00: Tags attached to, or associated with, an object, in order to enable detection of the object (record carriers for use with machines having a detectable tag or marker G06K19/00) - G08B 13/2437: {Tag layered structure, processes for making layered tags} - G08B 13/244: {Tag manufacturing, e.g. continuous manufacturing processes} - G08B 13/2442: {Tag materials and material properties thereof, e.g. magnetic material details} - H01F 1/15308: {based on Fe/Ni (H01F1/15325 takes precedence)} - H01F 1/15341: {Preparation processes therefor} - G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract A semi-hard magnetic element is formed of an amorphous soft iron-metalloid material containing at least 50 atomic percent iron and at least a part of the bulk of which has been crystallized to give the overall element semi-hard magnetic properties. ## Claims ### Claim 1 A magnetic element comprising an amorphous magnetically soft iron-metalloid material at least a part of the bulk of which has been crystallized to give the overall magnetic element semi-hard magnetic properties, said amorphous magnetically soft iron-metalloid material containing at least 50 atomic percent iron. ### Claim 2 (depends on 1) A magnetic element in accordance with claim 1 wherein: said amorphous material contains between 50 to 90 atomic percent iron. ### Claim 3 (depends on 2) A magnetic element in accordance with claim 2 wherein: said amorphous material further contains silicon and boron. ### Claim 4 (depends on 3) A magnetic element in accordance with claim 3 wherein: said amorphous material is of the nominal composition Fe.sub.78 Si.sub.9 B.sub.13. ### Claim 5 (depends on 1) A magnetic element in accordance with claim 1 wherein: said magnetic element has a thickness in the range of 20 um-50 um. ### Claim 6 (depends on 1) A magnetic element in accordance with claim 1 wherein: the coercivity of said overall magnetic element is greater than about 50 Oe. ### Claim 7 (depends on 1) A magnetic element in accordance with claim 1 wherein: the coercivity of said overall magnetic element is at least an order of magnitude greater than the coercivity of said amorphous material before said amorphous material is formed into said magnetic element. ### Claim 8 A method of making a magnetic element comprising: providing a magnetic element comprised of an amorphous magnetically soft iron-metalloid material containing at least 50 atomic percent iron; and annealing the amorphous material for a time and at a temperature sufficient to crystallize the bulk of the material to give the overall magnetic element semi-hard magnetic properties. ### Claim 9 (depends on 8) A method in accordance with claim 8 wherein: said amorphous material contains between 50 to 90 atomic percent iron. ### Claim 10 (depends on 9) A method in accordance with claim 9 wherein: said amorphous material further contains silicon and born. ### Claim 11 (depends on 10) A method in accordance with claim 10 wherein: said amorphous material is of the nominal composition Fe.sub.78 Si.sub.9 B.sub.13. ### Claim 12 (depends on 11) A method in accordance with claim 11 wherein: said annealing temperature is in a range from 500.degree.-750.degree. C.; and said annealing time is in a range of 3 minutes to 2 hours. ### Claim 13 (depends on 12) A method in accordance with claim 12 wherein: said annealing temperature is in the range of 625.degree.-650.degree. C.; and said annealing time is about 3 minutes. ### Claim 14 (depends on 12) A method in accordance with claim 12 wherein: said annealing temperature is in the range of 620.degree.-640.degree. C.; and said annealing time is about 10 minutes. ### Claim 15 (depends on 12) A method in accordance with claim 12 wherein: said annealing temperature is in the range of 575.degree.-600.degree. C.; and said annealing time is about 30 minutes. ### Claim 16 (depends on 12) A method in accordance with claim 12 wherein: said annealing temperature is at about 650.degree. C., 650.degree. C. and 625.degree. C. for annealing times of 3, 10 and 30 minutes, respectively. ### Claim 17 (depends on 12) A method in accordance with claim 12 wherein: said annealing is in an atmosphere of one or more of an inert gas and air. ### Claim 18 (depends on 17) A method in accordance with claim 17 wherein: said inert atmosphere is one or more of nitrogen and argon. ### Claim 19 (depends on 12) A method in accordance with claim 12 further comprising: applying a magnetic field to said amorphous magnetic material during said annealing. ### Claim 20 (depends on 12) A method in accordance with claim 12 wherein: the coercivity of said overall magnetic element is greater than about 50 Oe. ### Claim 21 (depends on 12) A method in accordance with claim 12 wherein: the coercivity of said overall magnetic element after said step of annealing is at least an order of magnitude greater than the coercivity of said magnetic element prior to said step of annealing. ### Claim 22 (depends on 8) A method in accordance with claim 8 wherein: said material is of a given thickness; and said method is conducted exclusive of any steps for reducing the thickness of said material. ### Claim 23 (depends on 22) A method in accordance with claim 22 wherein: said thickness is in a range between 20 to 50 um. ### Claim 24 (depends on 23) A method in accordance with claim 23 wherein: said material is in the form of a flat ribbon or strip. ### Claim 25 (depends on 22) A method in accordance with claim 22 wherein: said thickness is in the range between 20 to 50 um. ### Claim 26 (depends on 8) A method in accordance with claim 8 wherein: said material is in the form of a flat ribbon or strip. ### Claim 27 A tag for use in an EAS system comprising: a signal generating first magnetic element having an activated state in which the signal generating first magnetic element is able to interact with an applied magnetic field and a deactivated state in which the signal generating first magnetic element is disabled from interacting with said applied magnetic field; a second magnetic element disposed adjacent said signal generating first magnetic element for placing said signal generating first magnetic element in said activated and deactived states, said second magnetic element comprising an amorphous magnetically soft iron-metalloid material at least a part of the bulk of which has been crystallized to give the overall second magnetic element semi-hard magnetic properties, said amorphous magnetically soft iron-metalloid material containing at least 50 atomic percent iron. ### Claim 28 (depends on 27) A tag in accordance with claim 27 wherein: said second magnetic element has a magnetized state and a demagnetized state which place said signal generating first magnetic element in said activated and deactivated states, respectively. ### Claim 29 (depends on 27) A tag in accordance with claim 27 wherein: said signal generating first magnetic element comprises an amorphous magnetostrictive material. ### Claim 30 (depends on 27) A tag in accordance with claim 27 wherein: said signal generating first magnetic element comprises an amorphous ferromagnetic material. ### Claim 31 (depends on 27) A tag in accordance with claim 27 wherein: said amorphous material of the second magnetic element contains between 50 to 90 atomic percent iron. ### Claim 32 (depends on 31) A tag in accordance with claim 31 wherein: said amorphous material of the second magnetic element further includes silicon and boron. ### Claim 33 (depends on 32) A tag in accordance with claim 32 wherein: said amorphous material of the second magnetic element is of the nominal composition Fe.sub.78 Si.sub.9 B.sub.13. ### Claim 34 (depends on 27) A tag in accordance with claim 27 wherein: said amorphous material of the second magnetic element has a thickness in the range of 20 um-50 um. ### Claim 35 (depends on 27) A tag in accordance with claim 27 wherein: the coercivity of said overall second magnetic element is greater than about 50 Oe. ### Claim 36 An electronic article surveillance system for detecting the presence of a tag in an interrogation zone comprising: a tag comprising: a signal generating first magnetic element having an activated state in which the signal generating first magnetic element is able to interact with a magnetic field and a deactivated state in which the signal generating first magnetic element is disabled from interacting with said magnetic field; and a second magnetic element disposed adjacent said signal generating first magnetic element for placing said signal generating first magnetic element in said activated and deactivated states, said second magnetic element comprising an amorphous magnetically soft iron-metalloid material at least a part of the bulk of which has been crystallized to give the overall second magnetic element semi-hard magnetic properties, said amorphous magnetically soft iron-metalloid material containing at least 50 atomic percent iron; means for transmitting said magnetic field into the interrogation zone; and means for receiving a signal resulting from said signal generating first magnetic element of said tag interacting with said magnetic field. ### Claim 37 (depends on 36) An electronic article surveillance system in accordance with claim 36 wherein: said signal generating first magnetic element comprises an amorphous magnetostrictive material. ### Claim 38 (depends on 36) An electronic article surveillance system in accordance with claim 36 wherein: said signal generating first magnetic element comprises an amorphous ferromagnetic material. ### Claim 39 (depends on 36) An electronic article surveillance system in accordance with claim 36 wherein: said amorphous material of the second magnetic element is of the nominal composition Fe.sub.78 Si.sub.9 B.sub.13. ### Claim 40 (depends on 36) An electronic article surveillance system in accordance with claim 36 wherein: said amorphous material of the second magnetic element material has a thickness in the range of 20 um-50 um and is in the form of a strip or ribbon. ### Claim 41 (depends on 36) An electronic article surveillance system in accordance with claim 36 wherein: the coercivity of said overall second magnetic element is greater than about 50 Oe. ### Claim 42 A method for detecting the presence of a tag in an interrogation zone comprising: providing a tag comprising: a signal generating first magnetic element having an activated state in which the signal generating first magnetic element is able to interact with a magnetic field and a deactivated state in which the signal generating first magnetic element is disabled from interacting with said magnetic field; and a second magnetic element disposed adjacent said signal generating first magnetic element for placing said signal generating first magnetic element in said activated and deactivated states, said second magnetic element comprising an amorphous magnetically soft iron-metalloid material at least a part of the bulk of which has been crystallized to give the overall second magnetic element semi-hard magnetic properties, said amorphous magnetically soft iron-metalloid material containing at least 50 atomic percent iron; transmitting said magnetic field into the interrogation zone; and receiving a signal resulting from said signal generating first magnetic element of said tag interacting with said magnetic field.