Magnetics Business & Technology - July/August 2019 - 6

FEATURE ARTICLE

Toyota Develops New Magnet for Electric Motors Aiming to Reduce Use of Critical RareEarth Element by up to 50%

Seeing a huge future demand for magnets in electric vehicle motors, Toyota researchers report a breakthrough in development of a magnet for
EV motors that uses 50% less neodymium and can withstand high temperatures. Pictured are the company's first all-electric autos to launch in
China unveiled at Auto Shanghai show in April.
Toyota researchers say they have found a way to dramatically
cut the cost of electric motors by reducing up to 50% the amount
of neodymium in their magnets in favor of less expensive and
more abundant rare earth elements lanthanum and cerium. They
can withstand the high temperatures in automotive systems, a
key factor for magnetic performance in a vehicle motor.
The company says its new magnet is the world's first neodymium-reduced, heat-resistant magnet and will become a key element of the foundation required to popularize electric vehicles. In
about five to six years, by the mid-2020's, Toyota expects to first
put them to work in electric motors for power steering, perhaps
also in robots and appliances. In about ten years, the automaker
expects to begin using them in the primary drive motors for electric vehicles.
This article provides details from Toyota about the magnet and
their development efforts which were conducted in Japan. The
magnet uses no terbium (Tb) or dysprosium (Dy), which are rare
earths that are also categorized as critical materials necessary
for highly heat-resistant neodymium magnets. A portion of the
neodymium has been replaced with lanthanum (La) and cerium
(Ce), which are low-cost rare earths, reducing the amount of
neodymium used in the magnet.
Neodymium plays an important role in maintaining high coercivity
which is the ability to maintain magnetization, and heat resistance. Merely reducing the amount of neodymium and replac-

Magnetics Business & Technology * July/August 2019

ing it with lanthanum and cerium results in a decline in motor
performance. Accordingly, Toyota adopted new technologies that
suppress the deterioration of coercivity and heat resistance, even
when neodymium is replaced with lanthanum and cerium, and
developed a magnet that has equivalent levels of heat resistance
as earlier neodymium magnets, while reducing the amount of
neodymium used by up to 50 percent.
The new type of magnet is expected to be useful in expanding
use of motors in various areas as well as maintaining a balance
between the supply and demand of rare earth resources. Toyota
plans now to further enhance performance and evaluate application in products while accelerating the development of mass
production technologies. This effort is part of a multi-pronged
program by the company to advance elemental technologies for
motors, inverters, batteries, and other components that are key
to technology advancement of electric vehicles.
Development background
It is important that magnets used in automotive motors and other
applications have high coercivity even at high temperatures.
For this reason, approximately 30 percent of the elements used
in motor magnets are rare earths. When powerful neodymium
magnets are used at high temperatures, such as for automotive
applications, terbium and dysprosium are generally added to
increase high-temperature coercivity. However, terbium and dysprosium are rare and expensive metals found in locations with
high geopolitical risks. Because of this, considerable efforts have

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